Interesting post, I'm about to make a pair of IEMs using the GV-32830 and I expect to get good results using dampers and a tuning circuit.
I did not consider the GK-31732 since it is said in this thread that the GV driver is a much better choice with vastly better mids. And that the CI drivers do not produce a satisfactory bass.
I have made earphones using GQ + RAB or 2x RAB and I wonder how a GK driver compares against GQ-30783 + RAB-32257?
The GK-33211 you mention is not sold by any vendor that I know of and doesn't appear to exist on the Knowles page either.