now I am undecided on what to do with batteries - seems that the more expensive ones, Thunder Power etc are lighter - and supposedly better quality - but the Zippy/Rhino have rave reviews around all the forums - although 50 grams heavier in the capacity range I am looking at.

do the cost benefits really outweight the weight penalty?  this is the question I find myself asking.....

also - would it be more prudent to buy LESS batteries but with faster charging rate (up to 5c) or buy more 1c packs?

on the question of charging - what is the best way to go for a charger? or two ?  would I need 2 to keep up with a days flying?

Another issue to watch is where you mount the batteries. If everything balances, then who cares if one battery is heavier than another--as long as you have enough capacityl

On the other hand, if you need to add weight to balance heavy batteries, then that weight needs to be added to the total.

I would really recommend making a battery mockup--basically for size--to see where you can fit it. Then as you are applying the last coat of finish to the model, order what you need. It doesn't help to have old stale batteries!

 If you like high rpm/low pitch props, you will probably go with capacities a little on the higher side. If you use higher pitch low rpm props, you will be ok with lower capacity.

I don't think it hurts to survey us when you have a real plane, ready to go. That way you will know your final weight (and know how sensitive you are to different battery weights and sizes. Also you can survey us to see what people are using that works well.

Well you can see what I use on a Vector 40 Arf in the sticky above. My total AUW is ~47 oz, charged and ready to fly. My battery fits right into the fuel compartment.