Hi X,
You may not like my response. :) This is both about the 2 apps and AAC in general. So, more info than you asked for but thought I would spew for a moment or two.
I ABSOLUTELY LOATHE TOUCH CHAT AND PROLOQUO2. Now, with that said, a lot depends on where your kiddo is at and where you want you kiddo to go on AAC.
When looking at AAC:
1. Hardware:
1a. Is it appropriate for my child's needs? If my child uses a wheelchair, is it wheelchair mountable? If my child is mobile, is it portable?
1b. Does it have a warranty?
1c. Does it have other functions that are needed now or will be needed - such as connectivity to a computer for schoolwork, making phone calls, etc..
1d. Does it have the type of access my child needs - direct select, eye gaze, auditory scan. Does it have touch gradation for direct select where fine motor isn't 100%?
1e. Does it meet my child's needs if my child has vision issues?
1f. Is it durable? The school has gone through 4 iPads with Mason. We are on our second. This is with Otterbox protective coverings.
2. Software
This is the most important component and too often overlooked but is THE most critical. Most children cannot bounce between systems. Thus, if you start on one system and then outgrow it's abilities, you have to start all over with another that meets your new needs, essentially throwing out all of your previous work and/or stunting your child at the level the device stops.
2a. Does the system have a training path, i.e., a level to start on that is easier while you are learning and then advances?
2b. Does it have a symbol set (if non-literate) that is usable by the child, i.e., if the child has low vision, are the icons clear and concise? If using symbols, does the symbol also contain the word for literacy building?
2c. Does the company provide good learning materials that can be used at home/school?
2d. Does the layout of the system make sense? Most times, the easiest systems to learn are those that are the most limiting once learned.
2e. Does it have an appropriate amount of language so that the child can say what she wants to say? It's not okay to be limited to just nouns or just the pronoun "I".
2f. How much do I have to program into the system vs. is already in the system? I don't want to spend my days programming page after page. I want a program that has enough that my son can say what he wants to say, when he wants to say it and as fast as he can say it - regardless of what level he is now or in the future - and without my adding content. What I program may not be what he wants to say.
2g. Are icons and actions consistent across screens - i.e., are they in the same location from screen to screen? do they do the same action in each screen?
2h. For iPad users, you will really need to be careful if you have touch issues. Some apps are built that swipe like the iPad swipe which does not always register a user's touch. (Mason had this issue with the new Dynavox Compass app. Even if I wanted to use that app, it was not functional as he could touch the internal icons all he wanted and it would never register that he touched it.)
2i. Be leary of systems that only offer phrase based language.
2j. Can you trial it for little or no money before purchasing to make sure that it really fits your child and your family life?
One thing that I always do when looking at new apps is have a list of phrases that I try to find. If I can't find the phrases, I try to figure out why. If I can find them, I try to analyze how logical it was and whether it works long term.
a. "I love you mom" (present tense, common phrase, I pronoun, family member - These are basic icons.)
b. "She ate my popcorn yesterday." (conjugation of to eat which is still a core word, pronoun variation, fringe word for popcorn and core word for time orientation.)
c. "Do you want to go to the xx" (ability to ask/request, infinitive use of go, core word "want", etc...)
d. "Would you like to eat a green apple after dinner?"
And so on ~ about 10 statements that represent present, past, future tense, ask/refuse/direct/share.
Any system should have the basics - greetings, about me (name, age), food/drink, eat, want, hurt, help, days, time, color. BUT, a good system will have core words that allow the child to express themselves in all situations - greeting a doctor, talking about their dreams, etc...
SO, Touchchat.
With Touch Chat, the early levels are pre-literate (up to 20 icon selection I think). The levels are laid out poorly. Examples: It takes 4 hits to get the word "water". Pronouns are split onto two pages. You have to push an extra button to conjugate a verb. Some conjugations show up misspelled in the text display bar. There is no icon tutor to find the location of words. Then, when your child has mastered 20, if your child is still not literate, you're hosed as the higher levels require the user to be literate. What I find really frustrating about TC is the inconsistency. If you are using the preset path, the icon actions are the same. If you want to go outside the few core paths, they have access to other content but the icon actions are not the same. (The core path always returns you to the main screen after selection. The non-core path the user has to manually return to the main screen.) Icons are not consistently located.
Proloquo2:
I have not looked at this in a very long time. What I remember not liking is that it was not functional. My son could say he wanted a cheeseburger but he couldn't say that he wanted 2 cheeseburgers or that he didn't want mustard on them. Again, I'm sure it's improved in the last few years but I remember thinking that it was way too restrictive, way to focused on just want/need and "I". Think about all of the things we talk about that are beyond want/need/I and make sure that it can do that.
SO, with all of that said, I will tell you that I am a huge proponent of PRC. PRC was the culmination of a PHD linguist designing the language and an IT company building the hardware/software to support it. They are the oldest AAC company on the market and are really focused on long term independence for folks who need AAC at whatever level. It requires no programming by the communication partner but can be programmed if you wish. The system allows for individual word selections, phrase based selections and/or visual scene usage (hot spots on a picture that talk). The child can start at a very low level and work up to the adult level. They have an iPad version of their software (but it is adult level). (You can block out icons until you build up to that level.) It is difficult for users with fine motor or vision challenges as there are a lot of icons in a small screen. It is logical, consistent, portable.
PRC also has the Android platform Accent. It's not cheap - you do have to purchase it as a full AAC device. However, it has all the beauty of PRC software in a portable, Android based platform (for internet browsing, computer adaptation). They have low vision options built in as well and the rectangular shape means that direct select users have less OT demands (for icons up high). The case is super durable.