Hi Alan, apologies for the late response, have been away.
I don't think there is a need for different voice macro per mode. It would be useful to be able to select from a list with user definable names. In my case I would normally use one of two, a general fairly long cq call when working qrp and a contest style cq when on 2m UKAC contests. I can conceive of other cq calls if say working from a campsite in say France. If recording the message is simple then keeping the User interface and implementation simple with just one button would be perfectly fine.
The Elecraft K3 which i have used on a contest station has four memories each accessible via a dedicated button. A short press plays the message for the button once. A long press repeats the message continuously with a definable interval of receive between. A press of the ptt stops the playback and returns to receive. There is a maximum time limit so the messages cannot play forever by accident, and I think there is a maximum message length, which could be a good idea to prevent misuse