My 2 cents worth
We have a new Catalina 270 and went through the same dilema as you. After looking at all the handhelds, fixed mounted,plotting vs.non plotting,we settled on a choice of two.Both are made by Garmin-they have the best software,are easy to use and have good customer support. Based on the size of our boat(similar to yours),ease of portability,being able to be interfaced with either an autopilot or computer,we chose the Garmin GPS Map76 or the GPS 176C(which is what we bought) The 176c has a larger screen than the 76. It has a greater picture defination with more pixels displayed than the 76. Will accept Garmins new "Bluechart" chip or you can download from their CD roms. Has 8mb of mem. Has all the whistles and bells from anchor drag alarm to alams for offcourse,etc. Is portable so not only can it be used on the boat,but also in the car,and can be either used with batteries or wired onto your boat. It has the new WAAS GPS technology as does the 76. It does cost more than the 76, but I felt I was getting more for my money and the 176c had greater versatility than the 76. Check out Garmins web site. Raytheon,Magellean,Lowarce, all were a distant second to what Garmin offers.Good luck and fair winds.