I'm starting to look in to radios as well. I have a 20'. From some of the reviews I've read, it seems that the Standard Horizon GX1700 is the winner. It has built in GPS and supposedly no need for an external GPS antenna (as long as the radio is mounted in a such a place where it can receive the GPS signals).
If I remember correctly, if someone with a GPS/DSC capable radio hits the distress button, any other DSC capable radio will receive the GPS location and in the case of the GX1700, there is a screen that will display "as the crow flies" bearing to that position.
I've been going back and forth of fixed vs handheld. With fixed mount, I'll need to put an antenna up and based on FCC rules, the antenna has to be place at minimum 3ft away from any persons so that the RF exposure limits aren't exceeded. Having said that, that limits me where I can place an antenna on my boat and still be able to lay it down when needed. If I need to transmit, any passengers in the front stbd seat will have to move.