I purchased a pair of 2.4Ghz 9DBi antennas that are stupidly tall and probably too focused. Given that that change is in the mix too, direct comparison wasn’t possible however, I’ve reverted to the dual band antenna’s that came with the unit on the 2.4Ghz radio and I have a pair of Haucom Dual-Band antennas that I was using on the 2/5 card. My only method of testing performance is with WiFi Explorer on my Mac Laptop and desktop downstairs. That, and walking round the house with my iPhone pinging the router. All in all, not very scientific however, looking at the result, here’s what I’ve seen: Parity on 5Ghz, no change in signal level on WiFi Explorer but, coverage appears to be more consistent around the house - no dropt packets on iPhone where once there where reliable black-spots. 2.4Ghz has jumped a clear 7% on both mac’s from mid 80’s% to early 90’s% - and that with the factory antennas.
There’s so many factors that influence the result however, for $10US on a pair of antennas, it was a simple change, and I’ve removed a diplexor - which has to be good - even if the benefits are maybe only in my head