I have the 920. I keep checking to see if someone has written a downloadable app. Seems like the technology is there. Market is not big enough to make it a high priority I guess.
The Fenix 3 is essentially the tri dept and outdoors dept at Gramin sharing ideas and working together :-)
The fact that they have an indoor rowing app whihc only does spm for now is a decent indication that rowers are on their radar.
All as it needs is a few Olympic medallists to use and blog about the 910, F3 etc and every club rower will jump on board. I posted a wishlist of functionality on their help forums a while back and ANT+ was top of the list for the Fenix 3 to Concept 2. Ideally you want the watch to sync up with your Monitor and get spm, splits, power curve, watts etc..