Polar have just announced some newsworthy updates here: http://updates.polar.com/2015/04/dont-miss-a-thing-with-the-v800-smart-notifications/
In a nutshell you can now get smartphone notifications on the V800 – nice. The M400 now has Polar STRIDE support (that’s the cadence sensor not the STRYD power meter for running!). The M400 also has predicted satellite position caching – as with some other manufacturers. This will get a faster satellite lock on startup, it’s called AssistNow® Offline GPS.
Oh yes and 3rd party power meter support is enhanced.
All good stuff, showing that the Polar product continues to positively evolve.