Firehawk screen or white screen? Help

I have recently installed a Dwin Transvision 2 projector and have a very good 130" diag. picture projected on an off-white wall. I would like to get the best possible screen to maximize the image and I hear conflicting opinions about Stewart Firehawk screens. Dwin told me they recommend a Stewart Studiotech 130, but they don't seem to have any experience of Firehawks, perhaps because they are relatively new. Some people have told me that I absolutely have to get a Firehawk, but others say that the picture can be a bit dull and have generally found them unconvincing. Can anyone give me advice about this?
I have a Yamaha LCD projector that is 1280/720. This projector has very good black levels and lots of brightness. I purchased a Stewart Firehawk Screen which I am convinced has greatly enhanced the contrast levels. Around town here I have seen several rooms with various Runco and Sharp DLP projectors. The best of presentations have seem to have been those using Stewart Firehawk screens. Runco recommends these gray in color screens with their solid state projectors so as to enhance a very good black level to a great level. However they recommend the Studio Tec material for their CRT projectors...CRT's do not as a rule need as much help in the area of black level enhancement as do DLP or LCD... Tom
I chose the Firehawk because my DLP projector, the Plus Piano, has a fairly low light output (450 lumens). The Firehawk has a gain of 1.3 (like the Studiotech 130, I believe), whereas the Greyhawk has a gain of .95

If you are using an LCD projector, the darker screen material will improve apparant contrast. But don't opt for the Firehawk just because it's the "new thing". If your projector has moderate to high light output (1000 lumens or higher), you are probably better off with a Greyhawk.

FWIW, I'm very happy with my Firehawk...significant improvement over a white backdrop.