I have the teco 1/8. I don't know about ratings or efficiency. I got it because space is at a premium, and the opportunity to have two stage temp control with an integrated heater, and also to have my UV in the chiller, was why I got it.
Can't compare it to anything else, but so far so good. Hook up was simple. The tolerated flow is very wide so I have it on my return pump for now but later can change to a loop within my sump off a powerhead.
Seems pretty efficient. I'm in a hot climate and in a hot room. On initial set up, it took about an hour to drop my tank 3 degrees, but maintaining that temp seems pretty effortless. 90 gallons.