I've spent some time on a full tilt 06' 159 rev with all the slp work. Gawd it was a nice sled. Every time i rode it i felt like i wanted to buy it from the owner.
Makes for a very nice turnkey sled. It never had any power fade either. This wasn't on an R engine though.
The Cons are its as much money as a big bore. May not have the same power, but you know how big bores go. Some winners lots of losers.
For the guy who wants good power, and still be able to use off the shelf pistons for those, "where going to McCall or Island Park day after tommorrow and i just lunched a piston and its friday afternoon" moments.
Its one of those setups that doens't get alot of talk around here, Just becuase of the $2K+ price tag, but i don't think you can go wrong with it. Cool thing is you can sell all of the parts and probably make at least 50% of your money back. Maybe more.