I tried re-celling mine with AA-sized, tabbed NiMh cells but could not make them fit. The OEM cells were smaller (2/3 AA, I believe you call them), and after a struggle, I located some of those, and had a MUCH easier job of it.

I get about 2 hrs-2 hrs & 20 mins. from a charge. The same cells in a 270c will give a charge of about 3 hrs., and with no backlighting, 4+ hours.

Well worth doing and not especially difficult, apart from finding the cells.