I don't know what kind of gearing you have on your current bike and I think you should look there to see what gears you normally use.
My touring bike has 44-34-22 and a custom 12-34 cassette. I think it works fine, whether I commute, ride solo or tour. The only times where it could be low is if I were riding in a peloton with a group of strong riders pulling me. I don't often use my 22/34, but I find it nice to have when I climb a steep hill at the end of a long day. And I don't use my 44/12 often either. In fact, even my 44/14 is rarely used, because spinning it at 90 rpm means I'm riding at 37 km/h (700c wheels).
I would suggest that if you get the XT crankset and find the low end gearing totally useless, replace your cassette by a tighter one such as 11-25 or 11-28; that way, you'll get the same top end, a decent low end and closer, more comfortable ratios in between.
There is one single problem I see with that setup: according to Shimano, you "need" a mountain derailleur, and mountain derailleurs don't work with road-bar STI, just with flat bar shifters à la Rapidfire. However, you may use either a mountain or road front derailleur and shift it with a bar-end or downtube shifter (their front end work in friction) or with Campagnolo Ergo. I know also that some people are using "somewhat successfully" a road front derailleur with a STI shifter.
P.S. My touring bike has 44-34-22 with a 105 derailleur and bar-end shifters. Works great.