I personally have the Ericsson from AT&Tand it looses reception 2-3 miles out, for crying outloud I can't even call Malibu Sue or Larry The Duck at WLIR (92.7FM) and make a request while I listen to it on my boat.
My wife however has a Kyocera I believe from verizon with the extending antenna and the neat thing about it, although I didn't try it out on the water yet, it allows me to browse the Web ANYWHERE using the phone as a modem (not blazing speed, more like a slower 56K but heck can't have it all).
Just my 2 cents, I hope this helps...