Rating: 4 / 5
I have to wonder if some of the units out there are possibly defective judging from other reviews.
I've had mine since they first came out and I have apparently had a radically different experience testing this unit than some of the others.
I've used mine throughout tons of places where my standard GPS had a horrible time syncing and given 5 minutes I never had the spot fail to send a signal.
Here are the limitations as far as I can tell:
While moving it takes a while to sync if you just turned it on. The same is true for my Gecko 301. This is easily fixed by leaving the unit on.
You have to know what to expect to tell if it sent the signal. I keep reading about how people couldn't tell it sent, but I've always been able to see mine flash the acknowledgement if I wanted to verify. I just toss it on the ground while I'm cooking dinner and wait for the double flashes which are eye catching in the evening light.
I think a lot of folks are giving up and turning the unit off too soon. You have to plan on the initial GPS sync taking 4 minutes and then up to 10-15 for all three signals to go out (it sends 3 different times just in case, but filters it down to 1 for your emails & etc). Sure, if your on the move this isn't great since it's fix is slow that way. If however you are in an emergency your likely stationary anyway.
I've had luck leaving it on, hitting the OK button and just tossing it in the top pouch of my pack and the signal went through.
The good: I've sent over 100 signals now and have yet to have a single signal not go through, even in canyons, heavy forest coverage, in heavy snow/storm condtions and even cold starting it 1,500 miles away from the last point with no issues.
It also sipps batteries very lightly. The manufacturer claims nearly 1 year in standby mode, which is why I really wonder why people keep turning theirs off during trips only to suffer increased sync time. I've left mine on during dozens of trips - effectively weeks worth of on time and my orignal batteries have plenty of charge according to my multimeter.
Overall, my Gecko 301 is less reliable in signal fixes, as is my Holux GPS receivers I use for auto navigation.
For me, it works as advertised and it has actually gained my trust. Hitting that occasional OK button has given my family a lot of peice of mind so I get a lot less flak and they don't unnecessary worry nearly the same when I go solo.
I also need to state that I do not use the tracking feature. I've heard it's spotty but the manual OKs have been fine for me.
The only downsides to me are it could be a bit lighter, have a better message sent indicator and they need to not charge as much on the yearly subscriptions.