Well, your 10lb truck is actually relatively light. Both of my trucks come in a around 13lbs.

I'm runnng the 8L in my buggy, which doesn't weight a whole lot less than your maxx; however, the 8L really is too hot a motor. If you want to go with an "L" can motor, I'd suggest either the 10L or 11L. I would highly recommend going with the 8 or 9XL for your maxx with a MM speed controller. The Quark in very nice, or so I've heard, but I have 4 MM speed controllers and love them all.

If you are on a budget, I'd go with the MM esc, the 8 or 9XL and your choice of batteries. A pair of trakpower 4900s for the ultimate in performance or a pair of maxamps 8000s for great bang for the buck and more runtime.

If cost is no object, I'd go Quark/Neu 2.5D (or the 1Y is speed is your primary concern). The logic or general rule that I've been leaning toward, as I gain experience, is around a 2000kv motor for 4S and around a 1700kv motor for 5S, although a 1700kv motor will run very well and reward you with cool running and longer runtimes.

I do have to say that the 8XL has done very well in my Muggy and Monster GT conversions. I'd stay away from the 7XL for a truck setup. I think it's too hot in a truck for 4S and definitely not for 5S lipo.