I have had my RS800CX for two years and have been considering a switch to the 310XT.
Here area few things I’m considering:
I like the 310XT’s ability to automatically switch sensors. With the Polar, at each transition, I need to push a bunch of buttons to stop the watch, switch to the right the sensor, then restart the watch. It doesn’t take a lot of time, but it would be nice if it did it automatically.
I like a small watch for training. I have nicer, mechanical watches for when I’m not training so the look isn’t important. All things being equal, I like the smaller form factor.
The RS0CX doesn’t need to be recharged. I know that it’s not difficult to charge the 310XT, but I can almost guarantee (for me) that there will be a time that it gets put into the bag and forgotten until it’s time to ride. There is a greater risk of it running out of juice in the middle of a long ride.
I think that software is a wash, and there are decent training tools for both computers. I do think that the 310XT works better with web-based training tools (e.g. beginnertriathlete.com logs, etc)
I like the 310XT’s quick release bike mount. The RS800CX bike mount is just plastic piece that allows you to wrap the watch around the bars. It’s cumbersome in the transition, but the extra 5-10 secs don’t really affect my performance.
What I don’t like about the RS800CX is the W.I.N.D. sensors. They are only compatible with the higher end/expensive products (CS500, CS600). It would have been nice to get one of the inexpensive Polar bike computers so I wouldn’t have to move the watch from my wrist to the bars.
GPS mapping is probably a plus. I don’t have the G3 sensor so I don’t get the benefits of a GPS. To be honest, I really don’t need it. With the 310XT, you get the capability which I’m sure I’d use, but I’ve never really felt that I’m missing out by not having the GPS.
The Polar doesn’t support Powertap, but I don’t see myself investing in a Powertap anytime soon.
For me, I’ve probably invested too much in Polar to switch now. I have speed/cadence sensors for the rod and tri bikes. If an extra $350 starts to burn a hole in my pocket, I’d consider the switch, but for now, the Polar is fine.
I don’t know if I’ve answered any questions, but i hope I’ve given you something to think about.
Ray