you can also buy a Nitro 3.3 roller and convert your self, this way you have a steel chassis....that is if you like projects mine took nearly 1 yr to complete... it seems like the stock e maxx/ t maxx need to be upgraded to come to the level as a stock Revo
Personally I would get the E Revo! The thing was designed and tested on 6s to be sure it will hold up to the extreme power of a good BL system. As far as handling the E Revo is superior! The E Revo can be a good racer or basher depending on what you want to use it for. The inboard suspension is stellar as well.
for the e-maxx 3906 no choice to invest some $$$$$for the rought power of the mmm or a good brushless set-up...however the 3905 for my experience no need major upgrade to handle a lot of power...