Triggering a 406MHz EPIRB will get the SAR ball rolling, but it will not provide rescuers with your location unless it has an onboard GPS. It can take several passes in order to get a good fix. Having an EPIRB with a 121.5MHz beacon or a VHF radio will help them localize your position. That could still equate to a long time in the water. Getting an EPIRB with an onboard GPS can get rescuers heading your way in just a few minutes. That might be worth the extra $400 - especially if you're 17.5 miles offshore and you've been catching blues and makos all day
Doug, you are like my personal N.A.S.A. assistant, I knew you would come to the rescue and evaluate the specs for me, so thanks.