As far as wireless is concerned ROS 4.9 is better than 4.5 for Nstreme WDS. With 4.9 I get better CCQ, better startup (it does not seem to go through B before switching to G speeds) and no “excessive data loss” on links below 22dB SNR.
LOL, I was forced to upgrade all our equipment to 4.9 after 4.7 took two of our production boxes offline, and downgrading didn’t solve the problem. FWIW, we have had no issues with 4.9, though we aren’t doing anything terribly sophisticated with it: just bridging, WDS, VLAN, hotspot, nstreme-dual, and some minor scripting.