I have 40 of both the standard eneloop batteries and the XX version. The XX version are too wide to properly fit in the line 6 packs, and get quite stuck however the white 1900/2000 mah version work just fine. I mutalated quite a few of the XX's trying to get them out of the TPB12's. It is suggested to use rechargeable batteries 2500mah plus which is why i got them, however from my experience the 1900mah batteries are far more than adequate for a 6 hour period, about what I need them to run for in a theatre show. And when the packs are done for a show, they still read about 5 hours of life left on the packs. Plus they slide in and out easily, and can be recharged 3 or 4 times more than the XX's.
However, i found i have to tape the enclosure tightly shut to ensure the connection does not become loose whilst the pack is moving around, perhaps the eneloops are slightly shorter but i have not had the chance to put them side by side with the procell's. I have thought i may need to place a small spacer in to ensure that the lid on the pack remains in contact with the battery.
Does anyone have any thoughts on this?