I can't speak directly to either device but you should be fine. I know many cyclist use watches. Do a ride with both running and upload each one to see any differences.

As far elevation goes YMMV regardless of how new your GPS is.
My brother and I both use edge 810's while my dad has 1000. There twos are very similar elevation wise and mileage while my elevation may be as much as 300+ feet over just a 2000' wide. Same thing with distance. @ 50 miles I can be .7 miles less.

Here (Understanding Sport Device GPS Elevation Issues | DC Rainmaker) is an article about elevation calculations. It's 6 years old but I think still just as valid.