I've run MM escs in all of my trucks on 4S lipo and with an 8XL or 9XL will run great. I like the 9XL better for the track because it gives more runtime and is more controllable without having to be too careful with the throttle. With the 9XL, I actually get to full throttle sometimes on the track.

The amount of weight that you can live with greatly depends on the layout of your track. Since my tracks is on the small side and tight with all of the jumps immediately following turns, I go for the 4S packs. For short races, I run 4900 Kokams and for long races, I run a 4S2P 8000 pack.

I think that the truggy conversions are easier because of all of the room under the body. With a buggy, you have to take a bit more care in the placement of the electronics, not the mention the batteries.

I like running the truggies, but if you are a good driver, the smaller, lighter and more agile buggy will make for some very fast lap times.