Misterpink..
The SP is much quicker steering than the Strada, due to its steeper head angle. It's 40lb lighter too - and this is very noticeable in all situations. It's very chuckable for a Ducati. It feels an altogether smaller/more agile bike to ride. However, don't expect to be soothed by its suave road manners - because its in your face all of the time. It really is a bit of a beast!
So, if you value civility over the above, then the Strada's the one to go for. A lower bottom gear means moving off is much easier, and a higher 6th gear gives more relaxed cruising. Handling is excellent, if fairly 'lazy'. Brakes on my own bike are superb, despite them being 'bog standard'. (And how nice to be able to allow its engine to warm whilst donning helmet and gloves. SP won't do this - it has no cold start lever!)