100 shots or less is very little but perhaps normal when they are brand new.
The Sanyo XX totally rocks when using with flashes. I don't have a solid estimate since I don't uses flash a lot, but a good impression is, that they'll last for 300-400 exposures at full power using Metz 58 AF-II and Yongnuo YN-560.
Sanyo XX are the only rechargeables I have experience with (beside OEM), and I'm a bit more worried when using them with the camera. First and foremost because I apparantly wasn't fully aware how to get the most out of them and therefore have been experiencing mixed performances, but also because the battery indicator on the camera is so-so. It tends to be OK, but yesterday I got red battery indicator on both cameras after about 80-100 exposures. This is first time it has been this much off and I'm not sure why. It's most likely a firmware issue.
But obviously, the cameras kept going. I would have panicked if it wasn't for my past experience with the batteries