Thanks Jason. The Fi collar is pretty good depending. It doesn't do "real time" but it's pretty close. It also uses cell signal so only works where there is a signal. The day he got lost, he went down into a ravine and there was nothing. I had hit the lost dog mode, but got nothing because there was no signal.
Monday was a different story. I had gone back into where I lost him and got a ping from Fi saying he was on the ridge about a mile away. I made my way out there and was able to track him with Fi. I found his tracks and was following those, but they went back down into a ravine. Then Fi piged again and he was back up on the trail about a half mile behind me. The little fucker circled back around me. Fi kept pinging me with updates and I eventually caught up to him and saw him. It pinged a few more times and I was able to track him by following his tracks (and Fi's location) but eventually the battery died. By that time, I knew he was kind of hanging out in one area and could focus my efforts there.
Without Fi, I don't think I would have been in the right area at all. And if I was, I probably wouldn't have known. But, it depends on cell service. Further out, no it would not have worked. Where we were it was spotty but ended up working.
I would totally recommend it if you don't want to spend the cash on a Garmin collar, which uses satellite, and cell service is pretty good in your area. If that isn't the case, then I would save up and buy a Garmin.