I never moved to Version 7 because many were reporting speed problems, some necessitating new hardware or network changes.
And, no disrespect to Steven, but "pretty stable" is not what I expect from critical software.
AC is the only program that I have used to have so many issues with upgrades.
V7 and V8 require more memory and ARE somewhat slower. Not substantially, but slower.
Both were quite stable for me. I have no qualms about recommending them from a stability standpoint. I would recommend a good amount of RAM.
I must disagree with you on the last point. Microsoft does weekly updates. Major upgrades have been every 3 years. AC is responding to government requirements, which it must to remain competitive. When you look at the enhancements, I hope you can understand why there have been so many upgrades. No EMR can be static in this environment.