Yeah I've read before that Shimano is on the conservative side, so maybe you're right about the 34t cog.

This whole thing has got me wondering about the front shifting as well. The chainline should not be an issue with the 135mm deore rear hub and the deore crankset, if I'm not totally mistaken, they're kind of made for each other?
But, I'm starting to worry that the FD-4700 front derailer won't work with the deore crankset for two reasons:
1. The chainline, which will be wider that a road double, so I'm afraid the derailer wont be able to shift to the big ring even with the limit screw all the way out.
2. The derailer cage will hit the chainstay when in the small ring. I can moven the mouting point up the seat tube, but will that not affect the shifting negatively?

I've read that the Shimano cx70 front derailer could be a solution to this, since its aimed at the smaller cyclocross chainrings. I'm currently using the cx70 front derailer on my road bike, since it comes in a top pull version, and it works with the ST-4700.