An MGT 8.0 drivetrain is far from weak!!! Supposedly, you need to shim the diffs in them, but I've got gallons of nitro through mine and haven't had a single problem. It's also insanely tough. Their are a couple of mods you can make that are worth while, but definitely not mandatory. The MGT 8.0 is going to lose in the handling department to the XXL, but I think it's a tougher truck all around and the engine makes WAY more power. I would either go with the 8.0 or the XXL if it were me. If you plan on racing than the XXL is probably your best bet, but if you're just going to be bashing around the 8.0 is the way to go. Also, my MGT 8.0 handles AWESOME on a track now, but I've done a little work to it to get it there. I can drive it on a 1/10th scale track now with no problems.
Here are the mods I made to my MGT 8.0: NOVA head(definitely not mandatory, but worth it), RPM A-arms, FT aluminium shock caps, FT titanium turnbuckles(only got them because I found them on ebay for like $15 or something so I couldn't pass it up), dual tanks(just for longer run times between refueling), Kimbrough servo saver, and some progressive rate springs. I drove it for a LONG time before I did most of these mods with almost no troubles. I just wanted to take the truck to the next level. I'll post a couple of links below showing the MGT's toughness and power in comparison to a Savage.
Here is one that's a tug of war between an XL and an 8.0. The XL can't even touch the 8.0!!!!
http://www.youtube.com/watch?v=ShQN11HGj98
Here's some video of an MGT 4.6, which isn't even as tough as the 8.0, doing some insane jumping!! I belive it's bone stock except for the pipe!!
http://www.youtube.com/watch?v=HmoQW6YS0Ks
http://www.youtube.com/watch?v=ORPic...eature=related