I've not ridden an '08 on, but know that most have been happy with theirs. There also appear to be more track related parts available for later models too. Although I'm happy with my RR6 track Blade and has got me from the Novice group to Fast in 2 years. There is also a big difference in price once you jump to the '08 model. Both are fast popular bikes on track.
agree with you there, i run inters quite comfortably on my 06, but was just putting the feelers out to see if there was a big improvement in the later model ie 08 onwards. if there is not a lot in it i dont think i,ll bother as my 06 is now like the perverbial pair of comfy slippers. maybe if i was to upgrade it may be worth going to another manufacturer?