Thank you for the info Collin.
I currently don't own ZBrush so am not able to try it, but it may be helpful to know for future references.

I have created a model in separate geometry pieces which each have been UV-mapped and textured. I now want to group it into one object and have it share 1 texture rather than several.

In the end,...

I'm sorry to say I don't have an answer for what you're trying to do, however, if I may, I'd suggest you use bump/normal maps or even displacement maps in-place of individual tiles. It should lower...