I have a Neu 1509 1.5D 4500kv in my STe with a MM on 2 and 3S (only for short speedruns). The ESC tends to get hot, but the motor stays nice and cool. It's a real monster motor ;)
Speedrun on 3S:
[youtube]97fRouRU_EI[/youtube]
Mugen MBX6Te RCM + Mugen MBX6e RCM + Savage Flux XL FLM + MERV all with Spectrum DX3S || WTS&WTB