i have the sd1800 from sportdog. i compared everything, and had money been no object i would have bought a tritronics on reputation alone. however, after comparing all the products, i chose this sport dog model because it was a hell of a lot less money than the comparable tritronics, didn't have "too many" features that would either make it clumsy, break faster, or just generally be wasteful. this unit is waterproof, versatile, and simple to use on the fly, not to mention pretty tough. i've had mine, with two collars, for almost a year. it sees salt water on a regular basis and is usually getting dropped and banged around pretty good, and thats to say nothing of what the dogs do to collars themselves. most of all, the company was very cool to deal with. i had some questions about the add a collar feature and spent about an hour on the phone with the tech, very patient and knowledgable.
for the bang for your buck, can't beat this.