Rob,
Are you seeking manufacturers' specs, or actual measured weights from owners? If the latter, you might also ask people to include the type of wood used in the construction of their holders. AWB uses a number of different types of wood, with different densities, and I believe S&S makes some walnut holders along with their standard cherry. Given my own experience, I think you'll see some variability in weight, even with holders made from the same type of wood from the same manufacturer. If you're looking for owner input, I can supply the weights for my 7x17 walnut AWB holders, a 14x17 cherry S&S holder, and a 10x12 cherry S&S holder.
Also, are you only looking for ULF holder weights, or would you also be interested in other ELF (Exotic Large Format) formats like 4x10, 5x12, 7x11, Whole Plate, etc.? I have several 4x10 cherry Lotus holders as well as one from AWB.
Finally, and I'm not trying to make this more work for you, but you might also include weights of the standard "mass-produced" holders where available for comparison. I'm referring to Fidelity holders in 11x14 and 14x17 and Lisco holders in 4x10, for example. I know none of these are in current production, but they are/were the standard in these format when they were being made (and I've managed to pick-up a few new 14x17 Fidelity holders over the last couple years). I used to have several 11x14 Fidelity holders that I sold at a ridiculously low price by current standards. I do have several of the (VERY heavy) 14x17 Fidelity holders and a couple of the 4x10 Lisco holders if you'd like those weights as a reference for your database.
Kerry Thalmann
Really Big Cameras