For what its worth, I've never felt the need to get any of my lenses serviced and my 10D doesn't have an adjustment feature.

When the fuss over back focussing first kicked off on the DP forums I did some measurements and did find that some of my lenses weren't spot on all the time with a razor sharp depth of field.

But I can't say I've ever noticed it being a problem in real life. If there is anything holding back the quality my photographic output then it is me and not my lenses or camera.

That said, my 10D only has 6 megapixels, I expect any back focusing gets that much easier to see with three times as many pixels to peek at