Another consideration for CX frame comfort is riding position. Specifically, how far forward you are reaching has a big impact on comfort. This is often tricky with a CX frame for two reasons. First is that CX racers often want the frame smaller than what they might use on a road bike, second is that many CX frame manufactures adjust geometry to adjust for that desire and so have longer top tubes for smaller sizes of frames.
I find that I am comfortable when my arms are bent. If you are all stretched out, that is not going to be a comfort ride.
One way to reduce the length that your arms must go is to cut your fork high. What I mean is that the amount of fork tube that extends above the ster tube is of the order of 3 -4 inches. This has the effect of bringing your bars at or above the seat height. This can work better than using the short 90 mm stems.
So if you are able to specify the fork tube length you might want to make it longer and use spacers to compensate.
