The Personal EPIRBs also have to be held in the proper orientation for the signal to get out (at least mine does), while the regular EPIRBs will float upright on their own.
I have two internal-GPS EPIRBs on-board; one sealed up in the
liferaft, and one that I keep under the
dodger. I also have one personal epirb-with-gps, which I sometimes carry on my person. I may get more of these for the crew the next time VALIS
sails to
Hawaii.
The internal-GPS EPIRBs significantly reduce the search area over the non-GPS units. There are EPIRBs that will take an input from an external
GPS, but this seems like a poor option to me (I can see some advantages, but they are far outweighed by the disadvantages).
All of these EPIRBs transmit an additional beacon signal on 121.5 MHz. This can be used with radio-direction-finding
equipment for close-in locating. This frequency is no longer supported by the Coast Guard, etc, but it still may be useful in Search and Rescue operations.