i just finished a test.
i ordered a kingston 16gb class 4 card but decided to try out my old 4gb generic again. this time at 16/44.1 running internal mics+dpa phantom in the living room. just recording the tv and ambient room sounds.
i also decided to see how long i could power the R-44 on four Energizer rechargeable (2300mh each).
running 4 channel (internal+phantom) i got exactly 3 hours before the "low battery" warning showed up.
not bad if i want to just run a stereo pair for a single show with a light bag. i'll still run my external battery with these AA's as backup, but that's good to know nonetheless.