I was using a 120l square esky from my boat, but with a bit of a warp in the lid i was having a hard time holding temps and would find myself swirling the immersion heater round at the half hour mark. Obviuosly not ideal, so i chose a new box the same capacity but a different shape.
I went with an icetech model purely on the price and quality front. It beat the competition by over $100 on the 120l model, so was too good to pass up.
I made another copper manifold the same as the one from the square one (still hurt my head with Palmers maths) and sent away for a nice k type temp gauge (nice as in $16) and mounted it in.
A bit of dicking round and more head hurting with the clibration and i now have it going well.
I have only done 1 brew with the new box (and i didn't have the new thermo then) but it lifted my efficiency from 74% to 80% on that brew.
Hopefully that continues. B)