1. I am all about the latest and greatest. 2. Even without the SSA and under seat exhaust, the 899 IMO is AWFULLY nice. 3. The mods that I have done to my 2011 848 EVO in the last year are; AKRA slip on's, OBERON clutch slave, WOODCRAFT rear sets, PAZZO shorty levers, grips & bar ends, a 14 T front sprocket, ZG windscreen, seat cowl, fender eliminator and integrated turn signals.
Because I bought my bike at a very low price and because I am finalizing the last pieces of a divorce, I considered selling my bike to buy the LATEST & GREATEST model. (For me an 899.) I have decided against buying new and having to start the mods all over again. Your situation is different, but I am very happy with my decision.
Also, I don't go to the track, but buying a brand new bike for the track IMO would be the second of the two options that you posted. FWIW For the track, I would modify what you have.