32H 2x rear wheel for velodrome - is it ok? I'm building new wheelset for my track bike which I am going to use on velodrome only. I have H+SON SL42 rims and Miche Primato hubs, 32H. I've ordered some cheep spokes and suddenly realized that I calculated spoke length with 2-cross pattern. 

After some investigation I've found that 32H wheels are being built with 3x pattern, 2x is used for 28H and for 32H it may be less stiff and less durable. Is it really serious problem and will I feel the difference? And is it worth ordering new spokes and making it 3 cross pattern?

For the front wheel it does not matter, it can be even radial as it does not transfer the power from chain, but the problem is about rear wheel only.
There is no hard and fast rule that matches spoke crossing to spoke count. It's more of a continuum. More spokes and more crossing = More durable wheel. Less spokes and less crossing = lighter wheel (possibly more aero as well). 

So you can build up a 32h 2x wheel and get wheel that is not quite as durable as a 3x wheel. You don't see this in production, because the weight savings is minimal and people choosing 32h tend to want a durable wheel.

I've build a couple of 32h 2x wheels for myself just because the spoke length for 2x matched the supply of spokes I already had. They are on my MTB and have had no problems for several years. 

Similarly, you could build 3x 28h spoke wheels which would be slightly heavier and slightly more durable, but this isn't done because people choosing 28h have already decided that lighter is better. 

IMHO, the quality of the spokes and the build of the wheel is much more important than the difference between 32 3x and 28 2x.