to be fair, the ones who will definitely know whether there is a compatibility issue is apple themselves.
(although it does sound like a compatibility problem).
I get 300Mbps with 4965AGN on 5GHz.
What I think was important, I have manually selected channels in the router to be: 40MHz only, Wide channel = 38, standard channel = 40. This is because only then my 4965AGN was able to see and connect to 5GHz. It's because channel 40 = exactly 5.200GHz. If you look at 4965AGN settings you will seethey mention 5.2 so I thought I set my router to use exactly this channel and suddenly saw 5GHz network and was able to connect. Speed is 300Mbps. Both: router and 4965 have Frame Burst Enabled.
When I connect to 2.4GHz I get 144Mbps. It's strange because with other N router I could only get 130Mbps, never more.
Notice: in 2.4 mode 4965AGN does no do channel bonding, this is why it's limited to 130/144Mbps. This was limited by Intel. Buy newer card or non-intel to get channel bonding on 2.4 band.