I have a 4 year old GSP, and we live on the edge of town.  I let him out every morning while I get ready for work and he runs in the fields behind our house and has always returned to the house when called, with 2 exceptions.  This morning was the 2nd time in 4 years that he decided to head to town for a visit.  I have an E Collar on him anytime he is in the yard and when hunting and for the most part, he stays in the yard when the collar is on for fear of getting "Corrected".  This being said, after we found him downtown about 2 hours after he went missing, I started thinking about a GPS type collar.  Does anyone have any they use and would recomend?  What kind of range should I expect to find?  I am also going to consider keeping him tied up, but I really like him to be able to run for 20 minutes or so everyday and like I said, this has only hapened twice in 4 years, but it scares the heck out of me when its hapened.  Thanks for any advice.