I've had a M3 Real since christmas, I had a M3 Lite Perfect before that.
So far, I absolutely love it. I don't care about Cheats(Which it has), Real time saving(Which it hasnt for NDS), Slowmotion(It has, but I never tried it), and all that other crap. All I care about is playing the games 100% like they're supposed to be played. Also, I have had 0! problems with all the games I've played, and Download Play works better than I expected. (You press Y to boot with improved DP Compatibility, instead of the Start button, No Safe Mode whatsoever)
IIRC The GBA Expansion does have a RTC in it, and has shown 100% compatibility for me (Well, except when you use games with built in sensors like acceleration, solar, and so on, because the Expansion wont have those).
The GUI can use some improvement, but I couldn't give a crap honestly, It looks nice and I don't mind if it's slow like other people say (I'm used to it) (It's a DS for crying out loud, not a PSP)
As for the bricking, this can happen with ANY FLASHCART that is not inserted properly(Very rare though!).. I recall my little brother stuffed in my old M3 Lite backwards (No idea HOW he managed to pull that off), which blew a fuse which I had to solder over to fix.
Corrupt SD Cards? Never had that.