After a lot of unrelated trouble getting the git tree kernel to actually boot, here is what I notice
1) The driver works! Thank you big time for that
2) Messages as the one below () no longer appear
3) The reported signal level is lower. As the ap is currently ~1m away, the level used to be around 95-97%. Now it's 70-77%. Throughput seems to be unaffected, though.
4) I still get connected at 1M, having to manually set the rate to 54M.
5) I haven't tested this on the previous driver, but I tried to scp a 700Mb file to my server/ap. Initially, throughput was around 3.4MB/s as reported by scp, though it decreased to a steady level of 1.8. This is more or less the throughput rate with the old driver (see point 3), however I wonder why it didn't keep the higher level...
 Jul 22 101754 jekaterina kernel [496252.111875] phy0 -> rt2x00lib_rxdone Warning - Frame received with unrecognized signal,signal=0x0c, plcp=0.
All in all, I'm happy to have finally left 2.6.25-rc9 behind
Ad 3), I'm back up in the 90's. All by moving the antenna 2mm