I gave it some serious thought. Basically its the 3:1 gear set and a new case. You have to use the rest of you guts from your case but the new case is bolt in and almost the same dimensions. IIRC, its about $1,200 or so.
I decided not to as I use 2 high quite a bit and I would miss it. I still plan on going with a doubler.
If you want to be the king of the bling get the 3:1 203 along with your "normal" 203/205 doubler. Then you get 1:1, 2:1, 3:1 and 6:1 gearing option's. That would be the shit. As far as which doubler mines still laying on the pool table lol