I have a stock VX .18 and it is quite a bit Slower than my buddies Stock SH .18.
I also have a Modified VX .18 (air filter, header, Tuned pipe) and it is MUCH faster than the stockie.
The SH .18 seems to hold a tune a bit better than the VX .18. Both run at the same temps. Both will idle well, with a proper tune.
My Vx's seem to start a bit easier than my buddies SH, but that may just be the way I Prime my engines.
Sorry, no Dyno numbers to give ya, just my personal observations.