I might have to do that(sell it quick that is).
As far as it working any better, the only real change has been that the WNDR3700 hasn't completely locked up the network...
I honestly believe that it is an Ubicom issue that Dlink can't correct due to poor communication, or lack thereof, combined with the inability to recreate these issues in their lab. Heck they may even have to wait for the Ubicom engineers to "fix" the issues, then apply the "fix" to their software, which ends up breaking something else downstream.
All I know is, I've owned a DGL-4300(Great product), DIR-655(Great until the firmware fiasco, but luckily I sold it with a good working firmware, I think 1.11 and it is still running with out issues) and the DGL-4500, which until the firmware issues, was a decent performer for my 5ghz needs.
As far as waiting for the XtremeN 450, I will wait and see... but if you were to ask me today, I would have to say, "I'll pass to maintain the reliability of my home network, until Dlink gets their act together".