gracias seeds, this touches of course on the major major issue of being comfortable on a bike. Everyone is diff, with diff flexibilities, diff arm lengths, fitness levels (which do affect arm comfort as stronger core muscles play a part in arm comfort a bit too) etc etc, so to the OP, I wish you a successful stem change and that you are much more comfortable on your bike.

I need to mention again that my old touring bike, that I rode for 15 years and did many 3-4 week trips on, had a stem change right after I got it. I thought it was ok then, but always knew a bit closer would perhaps be better.....sure enough, when I got my new bike this summer and it was 1.5-2cm closer in reach, I am more comfortable riding than I ever was.