@ dru can fly!
You're right, it should be optional. I don't know why I didn't think of that last night
And yes, for basic comment swap it wouldn't be necessary.
Obviously I can't speak for everyone but, if I submitted a chaptered story for the proposed review swap, I wouldn't want someone simply clicking on the first chapter and writing me a 200 word review (the higher limit you suggested is a brilliant idea, by the way) based on that first bit, which they could do in theory. If I submitted a story with fifty chapters, I'd be happy to review a story of similar length and read a fair amount of it, because I'd expect someone to extend me the same courtesy. But yes, thinking about it, it should be optional. Being automatic or so specific about story length could be a deterrent for some.
It just seems unfair to only review the earliest chapters of a story. It has already disadvantaged some writers of longer stories from getting decent comments in the current swap and I don't see how extending the amount of words to 200 would stop that from happening; you can write a lot about the first couple of chapters of a story, but it wouldn't necessarily be very helpful for future chapters/full editing. Author's styles generally alter throughout the course of a story and plot development exposes more weaknesses and strengths than the opening does. So, maybe it'd be a better idea to have a rule where the reviewer must look at one or two later chapters, and specifically reference them in their review?
But if the higher word minimum, like you suggested, and a genre tag system is implemented then it should weed out a lot of the bad commenters anyway. Just a couple of ideas.
@darkfallenangel
Sorry if it seemed off topic. Maybe this cleared it up a bit?