It may be fun to try and compare your existing RTAS plug-ins with their AAX equivalents, it may also be good marketing by some of Avid’s competitors to suggest that AAX offers no real performance gains. However, in both cases, the comparisons may be somewhat pointless.
AAX is around now as Avid prepare to launch Pro Tools 11, that has always been the case. Avid have gone on record several times to say that Pro Tools 10 was simply a bridge to the future - that future is 64 bit. Not only 64 bit, but also a brand new Pro Tools - you don’t design a product from the floor up (which they had to do to take Pro Tools to 64 bit) without giving the whole thing an entire overhaul. Furthermore, it has been no secret that the plug-in architecture of RTAS needed a good revamp, our sources suggest that has been the case on a grand scale.
Therefore, no one is going to see what AAX can really do until we see the next version of Pro Tools, whatever that may look like and whenever we may see it.
Investing in anything using comparisons based on AAX performance in a 32 bit DAW is not a good idea - it may also mean you find yourself regretting a buying decision based on any such comparison. My advice would be to wait and see what AAX does when its in a 64 environment before making your buying choices.