Is the stripping guide size play a major factor in shooting your line smoothly and in achieving greater distance? and is the 6wt freshwater rod version designed the same as the saltwater rod version of the same exact model?
My opinion? The size of a stripping (or taming) guide matters. Whether smaller is better, or larger is better, or how high off the blank it is matters, is still an open question. Many people have their opinions, and they tend to be strong opinions. I have mine, too, but there isn't really an agreed upon answer as to what size and height a 6wt rod's stripper guide should be.
As far as saltwater vs freshwater goes, I'll let others answer that--I have only minimal experience fly fishing in the salt. I suspect the tiptop size is of more import when considering fresh vs. salt water than the stripper guide, but I'm sure others will chime in with better info.