Depends on the circumstances. Overall, the PLB is extremely reliable. The jury is still out on the inReach, just not enough data. Certianly they have numerous saves to their credit and you balance any potentially lesser reliability with the ability to use it to two-way communicate and have to balance that. My recommendation to clients at this juncture is always carry a PLB as back-up, Given the small size and modest cost, not a big problem for most. If you can afford the inReach subscription, you can afford the PLB back-up