I do have a clamp style connector but kind of moved away from it because unless the battery was very well aligned the cell would go flying across the room. The clamp is too tight, at least on the one I have. I'll have to try playing around some more. I did upgrade to stronger magnets some time back which was an improvement over the first magnets I used.
I did manage to run a series of tests at 500mA on 1 cell of each type. I'll probably add a second cell of each type to the tests to verify the one cell I used wasn't a non-typical one, but looking at the numbers I don't think that is the case. The results so far are interesting:
Amazon Basic: 2.16AH
EBL 2800: 2.12AH
EBL 2300: 2.04AH
Energizer: 1.8AH
Eneloop Gen4: 1.73AH
Capacity wise Amazon Basic and both EBL cells are almost the same. The biggest surprise is the EBLs where their 2800mAH and 2300AH tested virtually the same. Maybe at lower discharge rates the difference will be greater. The Energizer and gen4 Eneloops were pretty close, but from the manufacturer's data the Eneloops have a longer charge retention. In my opinion based on the 500mA test, unless every bit of capacity is important and the battery will be cycled fairly often and cycle life is not an issue Eneloop is the way to go. I should add a Duracell AA to the test since at 500mA load they seemed to have about the capacity of an Eneloop- one time!
On a similar note, I have tested a number of EBL Li ion cells in the past. Their 18650s do not come close to their rating and the length of the cell is shorter than an unprotected 18650 even though they claim the cell is protected. Oddly, their 26650 rated at 5000mAH tested right about 5000mAH. I don't have any other 26650s to compare with. I have 2 cheap ~$20 flashlights that can use a 26650 and their run times are pretty long, up to 12 hours on low which is still pretty bright with a nice white light. I keep one of those in the car with some other lights. Of the 2 lights I like the Gear Light best. It has a nice range of variable focus, can use a 26650, 18650, or 3 AAs- adapters included. I like that it uses 3AAs instead of AAAs. The 3 brightness levels pull 1.6A, 0.78A, and 0.4A. 3 brightness levels, strobe, and SOS modes. If anyone is thinking of playing with 26650s the Gear Light may be a good cheap way to do it- I like it.