in the r09 menu, is a setting for nimh batts. they work fine.
Don't quote me on this... But I believe that the menu setting is more for an accurate display of battery time left than anything else.
I've used standard batteries and nimh on the alkaline setting and have noticed no difference in the recording time I should get. Just a difference in the battery left display.
As a general note it is very much worth picking up a good set of rechargeables.... I use Sanyo 2700 nimh with my R-9 and get great recording times. I've never drained them totally in a live situation and usually swap them out at a fest when I get the feeling I should just to be safe. They will easily cover a regular show.
In fact to test the issue with the Transcend 8gig SDHC I used a fully charged set of the Sanyos and they lasted the entire 8 gig recording time at 24/48. They had a decent charge left on them when done... But I don't know how much as I replaced them with a fresh set to test the A-Data 8 gig card.