RE: triton2 and triton JR
Depending upon what you need and how much power you require. Here's a few differnces that if doing certain batts will be meaningless, but to other users doing a slightly different job would make the triton2 necessary.
Higher power, higher output voltage,adjustable threshold for nickels,higher current, more memory locations, settings are just more configurable on the original or the triton 2.
If the batts you'll be doing fall within the jr's specs then going to the triton 2 would be of no benefit.