I can't help with the dual band access points but I have just ordered a TP-Link WA901ND based on various favourable reviews (except for the need for a reboot now and then - no big deal for me) so will see how that goes. It is 2.4GHz only but does have PoE.

The other alternative I looked at was a Netgear WN2500RP range extender but that requires a powerpoint for a wall-wart and an existing wireless network signal to boost up. It will not take an input from a wired network on its RJ45 ports and translate it into a wireless signal i.e. act as an access point. It is dual band however.