I bought a Sportster 20 a while ago and its awesome...has front suspension so I can't comment on the harsh ride post. But I've zero dramas with it...and its starting to cop a little bit of abuse on MTB trails.
As far as Scotts being bigger than others...I dunno about that. They provide geometry guides just like everyone else. I got a XXL...but I based the purchase mostly on the BB to top tube measurement. It didn't feel any different to the same size cannondales and specs I tried.
My choice ended up coming down to (i) V-brakes vs discs (I wanted to save a little weight) (ii) the specs on the rear d and cranks were better on the Scott and (iii) I just thought the Scott looked a whole lot better!