I've been on the hunt for the "just right" rear axle adjusters for a while. Here's my experiences

AE: Bind the bearing, limited heights available.
IRS: Lots of range. Mold is a little loose in most bulkheads. Plastic is a little brittle and breaks often. Only ones I've found that go to 3.5
HB: Plastic is brittle. Mold fits most bulkheads snug. Two part numbers required to get the whole numbers and the increments. Only goes to 2.5.

What I wish we could get is the AE material in the HB mold shapes with .25 mm increments and with a range from 0 to 3.5.