This might be a case where what appears to be a downgrade might actually offer better IQ... Is your Tamron 17-50/2.8 the VC version or the cheaper non-VC? The reason I ask, many feel the non-VC is sharper across the board than the stabilized Tamron and offers image quality that's quite competitive with the Canon 17-55/2.8.
The Canon 17-55 beats the 24-105 for sharpness, so I'm pretty sure the Tammy 17-50 non-VR would too. The main disadvantage of the Tamron is slower AF... it's not one of the lenses they've updated to USD yet (similar to Canon USM). If and when they do that, it will be even more of a contender.
I'll tell you frankly, unlike some others I'm not a very big fan of the 24-105. I don't really need IS on these focal lengths. I use the 24-70/2.8 and 28-135 IS instead. The latter is far less expensive and so close in image quality to the 24-105 that you'd be hard pressed to tell the difference. In fact, the 28-135 has less vignetting at bigger apertures, at the wide end. It has very slightly lower resolving power and is a little soft wide open (f5.6) racked all the way out at 135mm, but good luck telling apart prints made with both lenses. The difference is that the L is better built and sealed. But I can buy three or four 28-135s for the price of one 24-105.
You might do comparisons, as best you can considering the different focal lengths, etc., at:
Seeing that you have a couple faster primes to complement it, you might be fine with a slower mid-range/walk-around zoom such as these. f2.8 is nice to have on a walk-around zoom for those times when you don't want to carry any additional lenses... but f2.8 also always makes for a narrower range of focal lengths. Only you can say which might work better for you.
There is also the new Canon 24-70/4 IS coming soon. It will be more compact than the f2.8 lens. Of course, it won't be cheap, though it's not as expensive as a 24-70/2.8!
If you didn't have the 10-22mm, and decided you can live without f2.8, I might suggest you check out the Canon 15-85mm, too. But since you have the ultrawide lens, this walk-around alternative might be too redundant. The 15-85mm offers top image quality in a relatively compact package. It's also a USM lens and has IS.