My LBS actually pulled out some devices and took measurements of me for the sizing on the roadie I purchased.
They never did this for any of the 3 MT bikes I purchased from them.
Something about being in 1 position for extended periods vs. the moving around you do on the MTB.
Anyways after all that measuring and doing calculations outta of book he came to the conclusion that I needed the largest frame and widest bars that they have.
I could have told him that right off.
Everything I buy for biking is always the largest they sell.
Makes things easy.