FWIW, I am presently running a rooted version of the stock ROM with the March, 2013 OTA completely installed. It is S-Off, Jbear hboot 1.58.5858 and 4ext recovery. After freezing 40 plus apps (mostly obvious stuff) and deleting the horrendous bolt sound and red boot animation for something a bit more calming, it is pretty good. I miss sweep to wake and the status bar battery icon isn't informative. The browser is very good. The setup isn't quite as slippery as Harmonia with Mac at 1512 mhz, but it is fast enough. It is probably as fast as Midnight 1.54 with its default 1296 mhz setting. Memory usage is very low, 332 MB right after booting up.
From the discussion here and in other threads there are many issues to be addressed for developers who want to build off the updated system. None of the custom kernels have worked for anyone, I tried Mirage and it looped. It is said that Leedroid Tweaks will not be compatible. Negaman has had problems with WiFi breakage. You also have to observe that many developers have moved on to JB projects and it is late in the game for this device.
I have only had it up for a day, so I will have to see what happens.