We run 5.10 on all of our legacy e1/e3k radios and it seems to be working fine. I don’t think they’re working anymore on the 4.x line, and so bug fixes for these legacy radios are being folded in to 5.x.
FYI… the asymmetrical uplink feature is only available on e4k radios. You can find details on how it handles legacy radios here: