Sorry,...slipped my mind to give an update.

So, the handlebar stem and new handlebar are perfect. I did a short (about 6 mile) ride, and a few store runs. The stem flex is completely eliminated. And my riding position is aggressive enough to give me speed, but upright enough to not cause me any rotator cuff aggravation. Wonderful, fast, stable ride. And I even had room for my little handlebar bag. No more cellphone on my hip or in my pocket.

I must add that I will be changing the shifter cable, as it's a nightmare. I have so many issues with it, it isn't funny. I even pulled the cable out of the housing and applied industrial lubricant - didn't do much. I'll just get a nice kevlar silicon lubed one as a replacement.