If you ski mostly in the middle west you may be happier with a pair of Scream 10 Hots, see my review at:http://forums.epicski.com/showthread...ght=scream+hot
I grew up close to Traverse City Michigan, for conditions you normally find there (machine made refrozen skied up hard pack) the Scream 10 Hots should be about perfect. As per my review, these are great carving skis on hardpack. My understanding of the Xtra Hot is that these are a little softer and thus potentially a little better in the bumps and on powder.
At your height and weight I would go with the 175 if not shorter. I have last year's 187's. At that length I did not get the extra stability at speed that I was looking for and they are a little tough to get through the bumps. I'm 6'3" 220lbs and if I had it to do over again I probably would have gotten the 175's.
I could be wrong, but it was my understanding that Salomon is only making these in shorter lengths (165 and 175) this year. To be sure on length and model, if you have a chance, I would try to demo both the hot and the xtra hot in different lengths and see what you like best.
In closing, I really like the Hots, they are my everyday ski for all mountain hard pack conditions. I would check these out before you make a final decision.