I just bought a Losi 8T roller from Nitrohouse for $329 and I am in the process of a similar setup, I had a 1515 2.5d and a Flightpower 6s 5000 pack laying around. So far I am really impressed with the truggy....its lighter and a lower CG than my 10s Revo
I have the XT8 on 6s with the Neu 1515 Heli version right now. It is silly awesome, but you need to know that the end bell is much bigger than the typical Neu 1515. In order to make it fit, you'll need to use Mike's XT8 chassis brace. It raises the center diff up a tiny bit and therefore allows the Heli version motor to be installed. For that reason, I would skip the Heli. Besides, you really don't need the fan when it's set up properly.
I just bought a Losi 8T roller from Nitrohouse for $329 and I am in the process of a similar setup, I had a 1515 2.5d and a Flightpower 6s 5000 pack laying around. So far I am really impressed with the truggy....its lighter and a lower CG than my 10s Revo
If I were you I would just go with the Castle MMM combo. Get teh 2200kv motor so you can run the 6s through it. They go for about $280-300 for the ESC and Motor. The motors are co-made by Neu so they are great quality. www.holmeshobbies.com has them for around $280 and he ships quick!
The Monster has them right HERE also $280 and by far the fastest shipping.