They're similar, but to me a more accurate comparison would be the Ducati 1098 Streetfighter IMHO.
The 1100 SP HYM has taller suspension, seat height, bars etc. The SD and the 1098 SF both share similar seat heights, riding position egos and ground clearance while the SP HYM is more upright and taller all around. Not to mention, the 1100 is an air cooled motor too. While the 1100 SP HYM and SD
do both have similar riding intentions at heart, I still don't consider them to be in the same class like I do the 1098 SF. I think of the SD as being a streetfighter while the SP is more of an over-sized street supermoto.
Look up and compare all three models on Cycle-Ergo and you'll see what I mean.
Motorcycle Ergonomics