I've got an AP I'm testing with an R52 as the A client card, my laptop with a CM9 and a 2 test CPE with R52N.
All connect fine with 4.6 or 5 beta in A/N mode without messing with the basic rates at all. The N AP in question is running R2n and R52nH.
When you set your AP to B/G, do you have to disable G basic rates for a B client to connect? I never have, though I don't have much B hardware to begin with. Most of it has long since gone.
I test with 2xRB411/R52n (ROS 4.6). AP set to 5GHz a/n and client to 5GHz a.
Using manual data rates at the AP and selecting a Basic Rate HT MCS 0
the client disconnects and do not come back. Client is set to default
data rates.
So as expected Basic Rate means the client has to support this rate to connect.