Well, the minimum flowrate for the jbj mini chiller is 110 gph. So from the top of my tank, which is 30-40" from the ground, and I figure all the friction loss in the chiller and elbows, I'm looking at ~3 ft of head pressure. And since I like to oversize (but keeping in mind my tiny water volume), I'm looking at the Hydor L25 external pump. It is cheap and looks like very efficient. 10W will probably give me ~150 gph at 3 ft head. And I can always split the returns to lower than flowrate if needed.
I'm thinking of getting rid of my mini-jet as my return pump from the back chamber as well, and only use the external pump. I'll have to think about this though as I'm not sure my tank can handle the return.
The only problem with this is that I will need to drill the back of the tank to feed the external pump.