lots of good advice here
I think the ergonomics of the PLB are quite important.
being able to hold it - when your hands may be very cold,
is something to consider. Small may not always be better.
The Orolia group is heavily invested into the new MEOSAR technology,
and I feel leading the way in the return link capabilities.
Having handled several beacons, I liked the feel of the ACR unit,
but my personal preference is for the slightly larger units that McMurdo make
rather than the 220 - purely based on holding something
substantial in your hand. I think the "floating" capability may not be so important
in a PLB, as everyone points out, it should be secured to you or your lifejacket,
and if you need to deploy it, you will want to have it in your hand,
with the antenna having the best view of the sky as possible.
Great that the questions are being asked and if anyone on the forum
doesn't own a PLB yet I really recommend they get one.