I'm following the Hillman puppy program, and I'm getting close to the time when he introduces the collar. I've been doing probably too much research into this, but I can't help it. I've pretty much narrowed it down to the Dogtra 3500 NCP, Tritronics Pro 500, or the new Garmin/Tritronics Pro 550. I like the idea of having high, medium, and low available by just changing buttons. But I do like the price of the Dogtra as well as not having to deal with the uncertainty that comes with the Garmin buy out. Can someone with experience with these collars help me finalize this decision so that I can get one ordered in the next week or so?