I have been using the UniRoss AA Hybrio (2100mAh) rechargeables and have been very pleased with the results.
- I believe they are of the same Hybrid technology as the Sanyo Eneloops, and whereas a normal rechargeable does tend to lose its charge more quickly when not being used, the Hybrio has been retaining its charge longer.
According to the instructions, they are capapble of retaining up to ~75% of their charge after a year of not being used. This suits me as I will use the flash for an hour or so and then not again for another week or two. The current set in my flash that I have been using in this pattern was last charged about two-three months ago.