I have to agree with this point as I run a small business with 2 artists. They both use dual monitors and wish 3D-Coat supported them. The program can be dragged across 2 monitors but that does cause a few other problems.
I beleive that for the next major version 4.0 for example, Serious consideration should be given to dual screen support despite the difficulties involved in accomplishing this. I only say this because dual screen is a very common setup for professional artists. I do also understand that there is a lot of work involved in this and that pushing it too quickly could cause an avalanche of other bugs for many users.