Not sure myself, some other members have had both. Anything 30c and up would be fine I am quite sure. I wouldn't worry about getting 45C crazy, and if you're willing to ditch hardcases you'll have lots more fit options.
About the Nimh's, I have to disagree. The market for them remains for the same reason the nitro market remains... because a moron is born every minute. Those of you who actually enjoy nitro may disregard the previous statement...
They
are temperamental. And peaky. And nuclear hot when you're done.
Go ahead and try some in your Flux
You have a bad frame of reference. That's all. just get rid of them. Do it quick- band aid quick, and it won't hurt much.