I've got/had several crane stocks...I know that Elite 3600mah cells fit and it's a bit of a tight fit (i.e. if the wiring's thick or the shrink wrap was double thick it'd be a really tight squeeze). 3300's should fit fine...can't say about any of the others.
Are the diameters of the cells different?
Anyways...3000+ is plenty for all day shooting.
9.6V can be a pain in the ass so far as the middle pack is concerned. Might be just me, but I've never had much luck with not chopping up the wiring or cutting up the pack with the stock tube.