I use Silkolene 10W/40 and am perfectly happy with it, I didn't realise 10W/50 was recommended although I remember Topitoo saying thats what he was using.
From the Ducati.com website
Ducati uses Shell Advance Ultra with SAE 10W-40 Grade in all of its models.
http://www.ducati.com/bikes/service....ng&detailId=46