crafords are the way to go for focusers. they are super smooth and have zero slop in them. if you can get one as part of the deal then go with it. the GSO r&p focuser is ok tho. mine works pretty smooth now that i have pulled it apart and washed out all of the glue that they call grease, but then at the same time i have heard horror stories about the GSO r&p too... some are rough as guts (but these are few thank god). over all they are quite usable.
oh yeah and the $200 extra for the 10"... well the more aperature the better hey
what ever you can afford... when i bought my 8" it was the same price as the current 10"... i'd have bought the 10" if i was buying now, but it all comes down to ya budget