I used to work at a commercial lab that used Xtol for all b&w film. Since it produces relatively fine grain you would think it would scan well, and that was the opinion of the dedicated film scanning person there.
I am a bit of a novice when it comes to scanning, so I can offer no expert opinion, only what I've learned from others. It would make sense to me that to get the sharpness a true b&w film has to offer, you would have to actually resolve the grain. I remember Roger Hicks stating that you need true resolution in the realm of about 4800 ppi to do so successfully. I don't know whether that's true or not, but it makes sense to me. I have no clue what the actual resolution of the Imacon you have is, but a friend of mine uses one and his is 3200.
I've also heard Sandy King promote scanning in a single color channel, especially with negatives developed in a staining developer. I don't know if that would provide any benefits with non-staining chemistry too.
I hope that helps add to the confusion.
- Thomas