I noticed that D-Link UK released a 3.10RC027 firmware for the B HW rev only of the DAP-2553. It has also been posted to the WW GPL site as well.
I installed last November and it has been running fine. An IPv6 related security vulnerability was addressed, which interested me as we are using IPv6 only in our enterprise environment. The B rev is the only version capable of IPv6 and not so common, but for those of us with one I wanted to share.