Hi Phil -
I've been using the Garmin Vista for over a year - it's a little more money, but the compass feature is indispensible for long-range laylines and nice for clocking shifts, too. If you check some of the on-line warehouses, you can get the Vista for close to the same price as the models with less features. With the Vista, you also get more memory.
Also, spend a few bucks on the software to take atvantage of the extra memory and easier course planning or debriefing after you sail. It's cool to look at your track, and is helpful to see how you sailed the course.
No matter which one you choose, get an inexpensive waterproof bag - it's hard to use the joystick while it's in the bag, but despite claims of "submersibility," any GPS will suffer from exposure to salt and moisture.
Have fun - these are great tools.