dont put a crossbar. it only makes the bars less flexible and they bend easier. Fatbars/ Pro tapers are WELL WORTH THE MONEY. You won't be sorry. Yes they do flex. Thats why they dont bend. You can sorta feel them flex a little if u push on them really hard. They do help with fatigue on rough stuff because of the way they flex. The whole point of them is to not have a crossbar, so they DO flex. I reccommend these to anybody!
Im a somewhat tall rider I guess, and I like my bars high. I bought CR High bends, and have them really far forward. Pretty much straight up and down. I also have a 1/2" bar riser under my mounts with the offset forward.
When buying oversized mounts... ANY Rubber mounted ones will work. In fact, most of them saw KX/CR, or Honda/kawasaki rubber mounted. I had bad luck with the TAG ones, and bent the post. I then put a new bolt in, and it ripped the threads out. So I ended up bringing them to school along wiht my metal Cones... (another thing I reccomend... your bars still wont bend, but they wont twist either like with the rubber ones) and having them re tapped to the next AMERICAN sized thread. And then I just put a Lag bolt in. I bought a longer one so i could put in the risers also.
Good luck guys!