Main Motorcycle: 2012 Bonneville Black
Join Date: Oct 2012
Other Motorcycle: 14' MV Agusta Brutale 800
Extra Motorcycle: 2013 Honda CB1100
I have a 2012 diablo red Speed Triple and my cousin has a 2012 Ducati Streetfighter 848 in stealth black so I can offer some comparison. Hands down, the Ducati is the more exotic bike and people always seem to ask "who's ducati is that" when we have it parked next to each other. The Duc definitely draws a lot more attention, even from people who don't ride automatically know of the Ducati brand.
So if image and that kind of thing is important to you, it's no contest. The components and build quality also are better on the Duc and you don't really need to get anything aftermarket to make it look good. Where as I've put on flyscreen, bellypan, seat cowl, arrow slip-ons, etc to enhance the looks and make my bike look and sound better. The Duc's twin sounds great from the factory, no need to upgrade the exhaust.
With that said, both bikes are more than quick enough for street use. However, the Speed is much more livable on a day to day commuting basis. The ergos are way more comfortable and the engine is much more responsive throughout the entire rev range. The pegs on the Duc take awhile to get used to, from shifting to just over all cruising. And you are definitely in a more forward lean position in the Duc, so long rides will start hurting the wrists where I feel I could ride the S3 all day.
If you could afford to keep the Scrambler (I still kept my Bonnieville for in-town riding and just cruising around and looking good on), I would say get the Duc. You'll probably wind up spending 1K+ on the Street in accessories, so the overall price difference won't be as big. But if had only 1 bike, I would definitely go with the Street. It's a better overall bike and IMO the engine is more flexible. You'll probably have more fun on it too.