Winglift,

As you've observed, NiMh batteries are smaller than NiCd batteries. As you go up to larger mAh batteries, the difference in sizes increases as well. For example, the last 2000 mAh NiCd battery I purchased use sub C cells and the same size NiMh battery uses AAA cells. Both batteries will work up to their rated capacities. I'm not trying to start a lengthy argument here, but FWIW I've quit using NiMh batteries all together. I've had a couple receiver packs fail in flight with disasterous results. I think they are OK for smaller sport planes, but I don't think they can stand up to the vibration of a gas motor in a larger plane.

I hope I answered your question.........