What's the best Truggy motor/esc setup?

[GO-RIDE.com]

I currently have a Losi 8B with a MMM V3 and Medusa 60x2000 that I run with a 4S 4900 lipo. I runs well, but the Medusa gets a bit hotter than I like. My buddy has a Losi 8T with a MMM and 2200 Castle/Neu combo that runs on a 4S 5000 lipo. It runs really strong, but his lipo gets warm and puffs a bit on long runs.

I want to build a Truggy next and I have a few questions about motor/esc/lipo combos.
1. I'm torn between staying with 4S and a 2000kv to be easier on the ESC or going with 5S or 6S and 1400ish kv to be easier on the lipos and motor.
2. As powerful as the Castle 2200 motor is I'm not a fan of it's high amps, so I'm looking for something else. If I go Medusa should I be looking at a 70mm or 80mm? My 60mm 2000kv runs a bit hot (never over 170) in my buggy.