Hi JMC --
Which specific version of Go Button are you using on the older devices, and what version of iOS are they running? We aren't able to release patches for anything except the current App Store version unfortunately, but the last-compatible releases for a given version of iOS are all known to be fairly stable. (We try to make sure of that before we increase the minimum iOS requirement.)
Is Go Button presenting you with a crash report to submit on the older iPads? If so, please send that in and include your email address so that we can take a look. Perhaps we can figure out what is happening.
Also, if there is a certain audio file that is consistently involved in the crashes, you may try transcoding that file to a WAV or AIFF. Oftentimes a non-standard MP3 or M4A encoding is the culprit of many crashes.
Brent