the Infinity .18 definitely makes more all-out power, but the lack of a low speed needle makes part-throttle operation a pain. the advantage is, that's one less thing to screw up.

the VX18 seems (to me) to have a little more compression, and the general "feel" of the engine (powerband wise) just feels better-again, probably because of the low speed needle. It might last longer, it might not.

TST is dead-on about the SH motor though.