I think the difference here is motorcycle VS car. I am looking at the tracks from motorcycle standpoint, and a 250 2-stroke at that. Technical tracks are much more fun (for me at least) on my RS then big open tracks (kind of what I would call Thunderhill).
Now Thunderhill is a fun track when I ran my GSXR 750 on it, but for the 250 there were some areas where it was just get it going and take a nap for a couple corners. Sears Point got you working from turn 1 through 6 and then it opened up a little with some good flow from turn 7 down to 11. Of course now that most motorcycle racing uses a new turn 9 config the flow is broken up, but it's still a good flowing track. Just need to ignore the "safety issues" people always think about when Sears is talked about. Honestly I just never looked to the outside of turn 10? Not sure why people were looking out there, as the track was on your right, not your left
Anyways, back to the RS... If you can find a good NX5 with good spares I would go for it. You will enjoy it I am sure. People say it's a harder bike to ride fast then the TZ250, but it's easier to get to make more power (ye, that's all you need a harder handling more powerful bike
).
I do know that I dropped my RS off with Traxxion Dynamics and had them go through it and set it up. The bike is perfect so far. At jennings it was smooth as can be. Never had a misplaced wheel the entire weekend, never a push, nothing. At Barber I had some shake coming out of 5 through 6 but there are some pavement "issues" on line and I was heavy on the power with the front wheel way light. Just got up further on the tank and it kept on track just fine. If you need suspension work done, I highly recommend Traxxion Dynamics!
_________________
Charles Gallant