Figured I'd give an update on this.

I bought the ACR Res-Q-Link PLB from Amazon.com. I submitted the rebate form and received the $50 check about 6 weeks after mailing it. The build quality and design details of this PLB are impressive. It feels like a professional instrument, and the SPOT-2 feels like a cheap toy in comparison. I put a keeper leash on the PLB.

I paid the optional yearly fee for sending "I'm OK" test messages to up to 5 contacts. This is really useful for me because I do a lot of stuff solo and it is nice to help keep my wife from getting worried.

I have had pretty good results with the OK messages. You have to understand how the ACR PLB works differently for test messages vs. SOS messages.

- a test/OK message is transmitted 1 time for a press of the test button.

- an SOS message is continually/cyclically transmitted until the unit is turned off or the battery dies, which is 12 hours or so IIRC.

So the upshot is this: it is quite possible to send a test/OK message and have it NOT make it to the satellite. And it is quite possible for an SOS message sent from that same spot to eventually make it through. It depends on how visible the satellites are from your position, and this visibility will change as the satellites move through their orbits. I have had some PLB test/OK messages fail to make it through when sent from spots where I had towering mountains on both sides of me. I'd say that 80%-90% of the test/OK messages I've sent have made it through.

Still, I think in an emergency it would be worthwhile to move the PLB to a high spot with as wide and clear view of the sky as you can get before deploying it.