My son has a GSP pup that he would like to train for hunting. It's not his first GSP so he is comfortable with the breed but he would like to try an e-collar to help fine tune his pup. Any particular units to get or avoid? Through my job I have access to Sportdog brand but I don't know how they rate compared to others. He doesn't need gps or anything but I'm sure range will be a factor, those guys can cover ground in a hurry! TC