the updates include the ATK 450cc piston, crank and many other internal engine parts. The original dales usually didn't last long as far as the engine went, and I'm sure you notice the heaps of noises they make while operating. The new ATK's have fixed all of those problems. They also come out with Elka's replacing the ohlins/arvins on the C-dales and have Kenda tires replacing the holeshots. Of course none of this comes cheap - $10k price tag on ATK450's. They still have different versions (MX,XC) too.
Like I said before, if you have any questions ask Jeff @ http://www.quadshopatv.com/. He did alot of developing and has probably more seat time and experience with Dales/ATK's that anyone. He is a factory ATK rider in the GNCC series.