It's a decent engine, but an overall weak power band. On just about any track, the WS5's will pull harder off the line and into midrange then the Eco, and once you get rolling, the WS7's will pull harder. I would go ahead and spring for an S5, just because it is a much better motor, is only about 50 dollars more (on average), and if you need more top, just run a top end pipe.
Also, check out the JP engines. I run on a tight track with an FX .21 B5-N, and it pulls harder through the corners than all the others except the OS V-Spec. JP motors are also very affordable (when you look at the life span of a quality engine), and last through about 6-7 gallons before needing a pinch. I have about 3 gallons through mine, and when it is installed in the buggy, I can't turn the flywheel with my finger easily at all.
Just my .02!