BTW, did you know that the T* coating on standard Hasselblad lenses block all UV and IR light? Look at the Zeiss page for the 250SA...it talks about the reasons that the "specialty" lenses aren't T* coated.
(look under the "More>" section)
Anyways, with SFX...I found that the film doesn't respond to IR like HIE, Konica, or any of the other "true" IR films. I have found, though, that SFX is a great film for taking portraits of women. Makes their skin look smoother and silkier. Using a B+W IR filter with SFX didn't do what I expected. It's a rather odd film. Kinda like an extend red film (like Tech Pan) more than IR-like.
Oh, and don't get it too warm. The base fog goes way the hell up!