I would definitely consult with the builder for things like diameters and wall thickness. If you are going to Waltly, I'm sure they have some limits on what they want to deal with as far as materials. Other contract builders will be the same.

A number of U.S. builders externally butt their tubes because you can buy or make tube grinders that will do it. I suspect the improvement in ride is mostly a matter of how much you think it's going to improve the ride. I don't know if any of the Asian builders do that, but in the U.S. it's a high price option.

As Andy says, you don't get to control the contents of your thread and I'm sorry if anything sounded elitist to you, but I'm at a loss as to what it might be.