I bought 16 NexCells back in July 09. I have been recharging them most every week since. I use them in a FRS radio that stays on all night for 4 nights and used to last 42 hours. About 16-18 ma usage. They are AAAs 800MAh capacity (750 minimum). They tested 776 on my C9000 when new. Now are testing much more poor. I still get 38-40 hours of usage though. I think break-in measures now about 615 or less for most cells. The impedance voltage check went from 1.65 to 1.95-2.25 for now. Yes, some are tricky to recharge on the C9000 now.
I bought 16 Duraloops in Oct 09 and did the same but this FRS radio seemed to be using 23-25ma and ran them down in 3 nights. I still get three nights after 9 months. The impedance voltage check has moved from 1.58 to 1.73 ish. Capacity was 835 new and now more like 725 now.
My recommendation? If you find NexCells for < 75% of what your best price for DuraLoops then maybe get them. Other wise get the DuraLoops or eNeLoops.