No problem! Bright side is you have a more accurate flat field to work with with 256! Looks like you have some targets to work with for trying out, which makes sense to me. One of the references that I referred to show a pretty cool before and after about how the author (Janesick) cleaned up a sine wave image by removing PRNU; for real world pictures one would have to experiment. I'll have to try some more with this as well; it looks like nice news about the functionality of RawTherapee, which I would like to try as well.
Some side notes. The flat-fielding process relies upon sensor linearity to work, which I think/hope is the case for our sensors. I got pretty good linearity with the D40. Also, flat-fielding can be used to do photon transfer measurements (measuring k, read noise, FW, PRNU) on 1 frame of uniform data, instead of the 2-frame differencing method. Both methods negate the effects of PRNU, and both can be done for comparison. Also, I would think that tables, as Bill notes, would have to be built up, which are going to be different vs F# if we also want to negate vignetting, but processing power being what it is I wouldn't imagine it being too bad. Pretty exciting.