I run a Losi Xcelorin 10.5T motor, and an LRP sphere ESC in my Lazer ZX5, and it's TOO fast for my track.
It all depends on track conditions, really.
But trying to stay on topic, I've owned a cheap Speed Passion sensorless cirtix system before, and it was actually a really good system. Speed Passion, in my opinion, walks that fine line of being grouped with Hobbywing, mainly for their lower end products, but if their higher-end stuff carries the same bang-for-your buck that the cheaper stuff does, it should be great!
"So I says to the guy: 'What good is yous' offer to me if I ain't got no virgins to sacrifice?!'
and den he jus' sorta looked at me all blank-like for a second, an' jus flew away."