Hmmm. I really don't know about during transfer, but I know if I try to quick carb an IPA, and purge a few times that I "lose" some aromatics. So I try to minimize that.
I think if you transfer under co2, that as long as you use just enough co2 to push the beer (like 2 psi), you'll rarely need the spunding valve and not have much aroma blown out.
This is just my thinking, though! I have absolutely no practical experience in this!