Motorcycle Safety & Driveability: Which motorcycle?, race, TZ

Question
Howdy,
I race motocross, and currently ride a 250 two-stroke that is highly modified. My brother has bought and modified a sv650 to do track days and race, I went to the gp in indy last year, so I of course am beginning to think that this would be really fun! I have only rode about 200 miles on brothers 2004 superhawk as far as street experience goes... I really loved that 90 v-twin though, at least for the street. Anyway, I thought about looking into a rs125, I figured it would be an excellent starter bike, but I don't know how long it would keep me satisfied, and I don't want to just go and by a different bike next year, although that's probably inevitable. I think something like a tz250 would be freakin' sweet, but how much maintnance is really there, or does my brother have the right idea with the sv or an r6? Any advice you could throw my way would be much appreciated.
Thanks

Answer
It kinda depends on which race organization, what classes they have available for various bikes. I think the RS and TZ are fun as heck, but those classes tend to be pretty small. The 600 class is generally huge and there's always a lot of drama--novices, especially the ones who have no idea what they're doing, tend to drift towards the 600s. In the CRA (the club with which I'm affiliated) there's always lots of crashes in the novice middleweight (600) class. The 600s can be a handful, they spin that rear tire up way too quickly. You gotta really know what you're doing.

I'd go with an SV. The classes are relatively large, but the bike is more than manageable for a novice rider. Maintenance is relatively easy and cheap...the 600s burn through tires pretty quickly. You can get a race-prepped 2nd gen SV for less than $5K, or you could bare-bones it for little more than $2500.

Pat