Just to clarify:
If you increase the BB then you need to do it for all wheels.
I run RP25 wheels as well as AG wheels at 16.7mm BB through checkrail gaps of 0.9mm with few issues (so far!).
I nearly forgot!
I now remember the main reason I adopted the bigger back-to-back is so that rolling stock is better centred on the track.
This means that AJ couplings work much better.