I was killing time on YouTube and a video about the Polar Grit showed up on my recommended list. While I'm not going to run out and buy it for a variety of reasons, one thing I saw on the video seemed like a very good idea for the 945 level sports watch: Fuelwise. Basically the watch will tell you when you need to take gels and drink water. You can set it up to tell you every x minutes, or it can take your physiological measurements while your exercising and calculate it on the fly.
THIS is a feature I'd like to see on my watch. Perhaps Garmin can roll it out in a future software update.