My issue with the ACR battery is that you use up battery life if you subscribe to the "I'm OK" etc. messaging service. This option to send such a message is valuable to me. As a frequent soloist there are plenty of situations where I may not exit the woods at the agreed upon time but I'm not needing rescue:

- weather that had to be waited out

- unexpected difficulty with the terrain that slowed me down or forced a re-route

- delay due to helping out another party

That's why the Spot 2 keeps looking attractive. I know ETS isn't thrilled with the Spot 2 but there are other serious evaluations where it did quite well. BackPackingLight.com did one such eval, but it requires a subscription to read.