I can begin to answer my own original questions, because I went ahead and purchased the Wahoo Ace.
Advantages:
crisp display of much larger screen
much longer run time
audio navigation queues
Disadvantages:
larger unit size means it doesn't fit with some mounts
Much heavier (but only 8 grams heavier than my cell phone)
cost
Shrug options:
electronic bell. Works better when I'm not wearing gloves. Not easy to operate on a bumpy road
wind sensor. I've never used the data provided
touch screen. Unit still uses buttons for some actions.
I can display and very easily read 9 different data points on one screen. On the Bolt v2, I can display 3 and those are still a little hard for me to read. The display on the Ace is waaaayyyy better.
Paging between displays on the Bolt gets tiresome because you can only scroll in one direction.
The first two disadvantages I listed are understandable because the longer battery life comes from a larger battery and the vastly improved screen display needs a bigger screen.
I mitigated the cost disadvantage when I used REI dividends.
Overall, I am quite satisfied with the unit. It solved the problems I was hoping it would. I'm looking forward to not having to worry about recharging a gps unit on 300 and 400km brevets.
rob hawks