I don't see how I could EVER get bored of a 650. I have never ridden a 650 of course, but from from the videos I have seen, it's a wicked fast bike, more so than I would ever be able to use. If I did buy a 650, I would never go any bigger. The 500 I am not sure of. Some people say they get bored, some say their 500 is still their fun, go to back after owning nicer bikes. It's a bit confusing though, as the Ninja 500 is listed as having 59hp, versus the 65hp-72hp of the two 650s. Doesn't seem like much of a difference. More torque of course.
mmmnaked... can you explain what it was about the power delivery that makes you strongly recommend it over the 500? Unfortunately I don't think I'll have a chance to try either before I buy, as most people don't allow test drives.
I started on an SV650 in 2009, and I absolutely LOVE it.
I decided to get the SV as my first bike for several reasons:
1) I find buying/selling vehicles a hassle, so with this I wouldn't get bored quickly; I'm in my 3rd season now, and still entertained by this bike.
2) I loved the idea of low-end torque: which is perfect for city riding.
3) I was initially more comfortable on a motorcycle than I anticipated, which I discovered during my RTI M2 course. I guess it was a combination of lots of bicycling experience (balance), driving stick and tracking my car (understanding power/weight transfer) and just overall comfort on two-wheels.
4) I knew ahead of time that I wouldn't be a super aggressive rider: some guys buy their first bikes knowing that they'll eventually want a SS. I dont really have that aspiration, as I simply enjoy the freedom of being on two wheels altogether.
5) Fuel injection = easier maintenance
6) I just so happened to find TWO of the EXACT bike I was looking for: 2004+ Naked, Blue SV... they were both extremely low km's, so I bought from the more flexible seller.
All that being said, I'm now aiming at upgrading to a naked Yamaha FZ8 as I believe a bigger motor will be better on the highway, and the suspension is definitely better, but since they're so expensive it might be another few years before I do so.