Brad: we have a 1200 on a 440/512/indy head ( 440-1) , wilson modded indy 4150 intake , little 625/270 cam/727/4.56 car- runs 6.37 in good air.
The twin blade picked up the bcar a lot over the 950 it had before , its been just deadly consistent .
The thing with the twin blade is that it gets up on the boosters at pretty low rpm and does so quickly so, pump shot/squirter tuning is a bit more critical on pure race cars - don't want to leave too rich.
Dom set this one up for us, not the guys that sell them and we haven't had a lick of issues.
All we had to do was final jetting and i think one high speed bleed change and Dom sent enough bleeds to go up or down two steps if memory serves.
Engine is a lot HAPPIER,

Is it as good as a Dom?
I don't think so, could probably drop some numbers with a Dom , however, this class only allows a 4150 flange carb so, its certainly a way to get more cfm if needed and, we needed it .
Vacuum numbers at wot are much better with the twinblade than they were with the Pro Systems 950.
Its a good carb , no issues, no crap parts, very good metering blocks and even those are better now.

I will have the duster done soon and plan on doing a back to back with it and a 1050 from Dom on a similar 512 and see how close they really are.

I can say, without qualms , if the car needs more carb and your limited to a 4150 flange, the twin blades definitely help.
I think they can get as large as 1450 cfm, heard rumors they have a body that will now do 1600 but have not confirmed that.

if your looking at one, let me know, also, you can get them with Dominator style boosters.