Members in general don't care about what forum software you're running. Macfora - a long time user of vBulletin - switched back to IPB and their community is thriving as ever. There will most likely be a deeper root cause as to why your members are unhappy. Do remember, whilst you can provide your members with hacks and tools to expand the forum software, the real root and reason people stay at a community is because it
is a community. That is what you need to work on in the long run by the sounds of things