Having ridden an old SS, a new SS, and two monsters on track this year I can honestly say they all handle completely differently! As far as I'm concerned my old SS handled the best (after I lashed out £500 on an ohlins), but this was mostly due to the increased rear ride height.
At 6'1" I find monsters with clipons to be a bit of a squash, so the longer SS seems to fit better. I also find it easier to get weight over the bars, which helps a great deal for front end feel.
Despite spending all weekend at Cadwell fiddling with the ohlins on the back of my new SS I couldn't get it to change direction anywhere near as quickly as my old bike. I think the whole bike needs lifting which'll mean thinner clipons above the yokes.
As far as comparing them to a 900, the key difference is the rear tyre profile. The 160 gives them a much more flickable nature that their bigger brothers (but not exactly rs250 flickable!), makes my 900SL feel like a bus.
Jools: You'll have to ride my SS when it's sorted. I think you'll find it errrr... lively!!
Cheers,
Ali