The general discussion on stems and bars has been great. I gotta remember to check in on this forum more often.
Think bar shape, flex, and setup is one of the most underappreciated areas of the bike. Wish the industry would put resources into a wide array of bars with different shapes and stiffness instead of some of the things they're focused on right now, like making everything electronic . . .
I've read Lee's book and other articles and thought about this a lot, but I always end up having to maximize other variables. I'm just over 6'1 (186cm) and always end up right in between a L and XL. I go with L for my trail bikes that almost always get ridden on nearby purpose-build "sustainable grade" trails and XL for big bikes that get taken to bigger mountains. I start with wheelbase, RC vs. FC, and HTA. Then I do some math to make sure I can get the effective reach and stack I want and can position the saddle somewhere that will give me an acceptable seated position.
I end up running riser bars on both (35mm OneUps) - on the L to preserve reach and on both to compensate for short stacks. Then more than a few degrees of roll back eats up a bunch of reach and costs me a bunch of stack. So the ESL or SHO is what it is. However, I find I can adjust to it just like adjust to different wheelbases, HTAs, etc. when moving between bikes.
I guess my point is that the lack of a L/XL or more sizes (or reach adjust headsets) creates challenges beyond merely effective reach and stack. Always jealous of people that sit right in the sweet spot of a bike size and. as practical matter, don't have a lot of these sorts of decisions made for them.