I think sub-C are the perfect compromise between output power and proper size to shed heat. I've tried paralleling those AA's and it helped, but still not as good as a decent sub C. Not to mention the weight.

Boo. It would be nice to have 9000mah capacity in a Nimh cell, but the overheating issue is worrying. What with 1/8 and 1/5 scale becoming more common place, I would like to see larger cells with more capacity, but like has been said, the manufacturers dont see the need yet.

There must be some type of "wall" to capacity in the sub-C NiMH cell. Seems like if you go much beyond 4200's, something suffers. Plus, with new and better chemistries out now and in the works, it only makes sense to concentrate on those.

That is very true. Its a bit like Digital tv- at first there were only a few manufactures, and prices were silly. Now there are tons of different makes & models to choose from and prices have come down loads. I may well have to look at getting some of the A123 type cells at some point- they seem very much like Nimh in how you use them, just need a cc/cv charger to get a 100% charge, and they last for over 1000 cycles..... way better Lipos in most respects.