Originally Posted by doctor_prox
Are you saying NiMHs are cheaper than NiCD but not as good? I thought they gave longer flight times
No, sorry for not being clearer - nimh's can deliver slightly lower voltage than nicads (even thought they are all called 1.2V cells). They do have a greater capacity than the equivalent size nicads (although may weigh more), but unless you get a good quality nimh you will probably pay a voltage penalty. If a plane is only marginally powered then this might be significant.
I fly a S&B Komet with 8 cell 1050 Kan packs (nimh). These are the same size at 600AE nicad cells, but are as good if not better in terms of voltage and current delivery - similar to the higher performance nicad of the same size (500AR).
This is not an aspect of the hobby I'm expert in - I know it's to do with higher internal resistence of nimhs, but who knows what that actually means (I'm sure someone else here will explain).
So, in response to the original question, I would say yes, get good quality nimh's rather than nicads. But do some homework first and work out what are good quality (high voltage and discharge) nimh's. Otherwise you might end up with cheaper cells that fly like a nicad pack with one less cell (in terms of voltage).