I can't comment on the 1B (without seeing which dimensions are giving it that grade... shallower pav. angle?) other than to say that 1B is still excellent! I would not dismiss a stone with a cut grade of 1B as long as everything else looked good. And it is possible to have 4X on the HCA and a non-1A cut grade. Just like it's possible to have an AGS0 stone that doesn't perform. I think in all likelihood, this is a fantastic stone. What are the rest of the specs? Do you have an IS image?
This is going to be an excellent diamond. It has two tiny abberations outside the 1A cut grade and that is exactly why it comes out 1B. Like I have said on the site, you pay a steep premium for a diamond in 1A (generally) and you ought to get what you are paying for. This is definitely NOT a steep/deep variety of diamond, such as one might find at the low end of AGS0 cut.....This diamond will look and perform in an excellent manner unless something in symmetry or polish is way off, and you did not mention these.