Didn't knew someone was around CM11 for the Blade. Job well done, I'll try it when I have the time.. But I wouldn't be waiting for a Eco CM11 if I was you! :)
Stability, speed and battery, I recommend first Eco CM7 and then Eco CM9.. I'm with Eco CM7 for the past 6/7 months, and still running smooth and stable. I recommend CM7 for those who just need the phone to work..
Effem app does not work in CM7, because the FM radio framework in the source code is different from CM7 to CM9..
The ZTE Blade kernel comes from Android 2.1 or 2.2, I don't remember, so it has nothing to do with CM7/Android 2.3. However, if you want stability and speed, I recommend Eco CM7 or Eco CM9 (if you want a more modern look and feel). I'm with Eco CM7 on my Blade for the past 6/7 months and everything is still running smooth and stable..
FM Radio (as used in CM9-CM10.1) has to be adapted to work on the Blade. Maybe you have to run some patches to set up those "FM" variables..
KonstaT usually has all the patches in a folder, try to search for them..