jerry is an authority on them , my ported saw from him is amazing,Ya, it would only be hypothetical guesswork on my part as to why the windows are different and without further study of the crankcase and knowing the crankcase volume then a larger window may cause sluggish flow or it may add volume to the amount of air fuel mix reaching the top end. It would likely reduce velocity, sometimes bigger is better but not always as there are many factors that affect actual power gains in these machines.
and he keeps a fleet of them for work crews ---------------------