Thanks Lauren, that looks like a deal that's hard to pass up. For several years, I've been carrying an inexpensive "Plastimo" knock-off thereof, which turns out to not actually have USCG approval. Though I think it would work.
Maybe worth noting that the sling is not the complete system. One also needs a means of hoisting the POB, in the sling, back on-board. Many of us probably feel confident that we can hoist a soggy crew with one hand, if needed. But the premise of the Lifesling is that the
large person might be the POB and a
small person might need to do the recovery. It turns out that the mainsheet suspended at the end of the boom (my original plan) does not actually lift high enough to get a POB, hanging in a sling, over the rail. (It might do, on a larger boat.) A halyard, lead fair to a primary winch might do the job. But the official method is to attach a block and tackle to a halyard, hoist it ten feet up the mast, then hoist the POB with the block & tackle, maybe plus a winch. Lifesling sells such a tackle, but I have enough extra line on my 4:1 vang - and snap shackles on both ends - to quickly deploy for that purpose. And it's always right there. I knew there was some reason that I never got around to trimming that line...
Anyhow, some kind of rigging that can hoist from the waterline to a body-length above the rail needs to be arranged, tested, and staged. If you don't have such rigging on deck, it might be worth adding the Lifesling tackle to your purchase. Probably useful for all sorts of other stuff, like dinghies, outboards, etc.
edit re: using the mainsheet and boom - also turned out that my topping lift is not up to the task. One would need to also run a halyard to support the end of the boom. It pays to work out these details in advance!