I was looking at Eneloop's, and was looking at the XX's, but after reading Sanyo's website, I am not sure about the XX anymore.
The latest standard Eneloop's are rated for 2,000 mAh (min 1,900 mAh) and upto 1800 charge cycles - that's a possible total of 3,600,000 mAh. But they also claim 90% capacity after 1 year and 70% after 5 years!
The XX version are rated to 2,550 mAh (min 2,450 mAh) and upto 500 charge cycles - which gives a much more disappointing total of 122,500 mAh. The claimed capacity after 1 year for these is 85%, but no other time-scales are mentioned.
So with all that in mind, is there any real benefit (apart from the extra 500 mAh in a charge) of the XX? It seems to me, that unless runtime is mission critical standard Eneloop's are better, and might even hold a bigger charge for a longer period.