Just open the following link and check if there are any new features you'd miss with A7: http://manual.3dgamestudio.net/beta.htm
For me personally A8 is worth it, esp. since I've bugged jcl a lot to implement many of said features.
Don't forget that bug fixes for A7 stopped with A8, and not all of the bugs fixed have been listed here: http://manual.3dgamestudio.net/bugs.htm

A8 pro is totally overpriced though, so you may want to try and find a used copy if you need A8 specific features or bug fixes.