[adouglas]

One of the defining characteristics of the Ninjette, and one of the things that makes it so much fun, is that it's light.

Both of the bikes you mention are stylish, but they're bricks by comparison. Heavy for the amount of power they produce. A quick Google shows me that the Street Twin, for example, clocks in at 460 lbs give or take with a full tank, but puts out only 55 hp.

Another thing to consider is that with a Ninjette, the fun comes from making it scream. Ride it around at 5,000 rpm and you're missing out on what makes the bike great; the party starts at about 9000 rpm and you can ride it like that, all day, every day, for years. I did and loved it. If you haven't been riding your bike like that, give it a try. You might gain a new appreciation for it.

Both of the bikes you mention are more relaxed, making their power and torque much lower. Big displacement, lazy thumping engines. So the riding experience will be very different. The torque will feel good around town and off the line... the Ninjette is more about momentum than grunt. But bikes like that really aren't about spirited riding.

Having ridden the FZ-07, I can say that in spirit it's a lot like the Ninjette. Feels nice and light, good personality, lots of fun. If I were buying a commuter, it'd be on the short list. But it's definitely in the modern-naked camp and doesn't have the retro vibe of the bikes you mentioned.

It's a matter of personal taste and priority. If cafe/retro styling is your thing, then you're fixed into a certain subset of the motorcycling universe.

Other bikes to consider in that vein:

Yamaha XSR900 (I rode one and loved it), the Ducati Cafe Racer. I haven't ridden one of those, but I sat on it at the motorcycle show and it just made me smile for some reason.

Also take a look at the new Suzuki SV650, or an 08 or earlier used one (ignore the Gladius and whatever it was that replaced it; they didn't get it right again until last year). The new one is more retro than the Yamaha FZ07, which it competes against. Great motor.

If a fun-to-ride bike is important (vs. a bike chosen for its style), take a look at track day threads and see what kind of non-supersports people ride. You see a lot of Ninjettes and SVs at track days. The occasional Ducati Monster, and maybe a Ninja 650 or two. Also some hypermotards, but that's a whole different can of worms.