With super large turbos, there are gains with the Morrison Fab over the FP, but the FP isn't going to hurt power on a 14b/16g frame turbo.
Given that back in the day, the thing was to get an Evo3 or 2g manifold (and port the crap out of it), and the FP basically puts you where a ported evo3 ends up (with a few advantages to boot)...
Seriously though, it's probably the best value for a stock frame turbo out there. The Morrison manifold is beautiful, but unless everything else on the car is tapped out, I don't see the benefit for a stock-framed turbo. Compared to all the other cast manifolds, I think the quality speaks for itself, if I were still running a DSM flange I'd have one on my car.