I wouldnt say the Tekin 17.5 is slow. Mine is fairly quick when I use it.
Something I really like with the Tekin Redline motors is they're sealed pretty well so if you run on a less than a perfectly clean track or are bashing they don't require as much maintenance as one of the motors that has openings on the can or exposed bearings. Pretty much the only maintenance that needs to be done on a Tekin motor is to pull the front off and clean and lube the front bearing and you're good to go again. I tried a Duo 2 for a short time and the amount of crud that motor collected inside in the short time was amazing.