Many thanks, pitchfork. I used water on one particularly nasty pipe and noticed no ill effects, but that was before seeing other folks warn about water. Thanks for giving me more insight into the matter.
I also take a lot of tobacco chambers down to bare wood. I go slow and move to progressively finer sand/polishing papers. I would always like to leave cake, but often the cake is so uneven or spotty that I feel going to bare wood is the least bad option. Certainly using a reamer on most of the pipes I clean up is out of the question. One part of the bowl wall would become gouged bare wood while other parts would still have a thick layer of cake.
Back to the subject of water, I have seen old pipe maker catalogs recommend wetting the bowl walls before the first smoke. I wonder if this is still advised by any pipe makers (at least the ones that do not pre-treat their bowls)?