in any engine the less mass of the moving parts the better acceleration and higer RPMs.

the pull start has an extra bearing, and a extra shaft tied to the crank so yes, the pull start will effect performance a bit.

if you are racing then every bit of power is needed but if you are not then you probably wont notice the diffrence.

also the reason they have the boost bottle on the non pull start is again... every bit helps when racing and they probably figure that if you use teh PS version then you probably arent racing so dont need that extra bit of power.