I have a DT Systems SPT 2420 I've had for 7 years. After the first season of training a young dog, the "nick" button became unreliable. I sent it in for warranty. It still works.
My take is that these Korean made collars offer great features not found on other brands, such as the ability to set any level to the "nick" and "Jump" buttons as well as the "rise" button not found on other makes.
The flip side is that the materials and quality are not on par with Tritronics.