Same here; Kay (KE7BGM) and I carry a slightly different model of the same unit for the same reason.
When I'm solo, bushwhacking out in the wilderness, I carry it. Even when we're together, we take it, because neither of us would be able to get the other out for a major problem, and cell service in S. AZ is marginal, at best. It's a very nice backup.
Lately, I've been taking the DeLorme in-reach, as well; that allows Kay or chasers to keep track of my position for SOTA purposes, as well as peace of mind.
Thanks for the reflector post.