its a personal thing. especially if you use dildo bars. i digress.. on my 2007 8500 trek it came with 6 degree 600mm flat bars. it was quite nice. but i have recently put 680mm bontrgaer carbon big sweep 12 degree bars on it.
i would never again use 600s or 580s... sweep is also a big difference. its why risers feel so good, so moto. it puts your shoulders in a nice attack position, rather than locking them in place like straight bars tend to.
i now find it much easier to climb really tecnical rock gardens etc, the wide bars give so much more leverage. on descents, they also are heaps better, especially around sweepy berms etc. i might not be going any quicker... but i am having heaps more fun, and the bike feels great. it took a week of riding to get used to the wide bar, but now i am hooked.
i am now impatiently waiting for my 660mm slasa moto ace 11 degree bar to arrive for my zaskar....its one of the few nice wide sweepy 25.4 bars that are available for the old retro rocket bikes.
sith that bar in your first post is crazy! it must have been so hard and tiring to try and ride that bike!