Do you mean the avg/pace or pace ?
Set it to lap pace and 1000m/lap , well its shows around 1020m sometimes but, that 3-4 sec isnt much.
But if it can be more accurate its better of course.
And this altitude problem , to eleminate the gps measurement error , Use SportTracks and the plugin "Elevation Correction", not perfect but better.
And same there , if the watch can calculate this more stable, great.
But this Beta-firmware looking good so far, with a little few tweaks it can be a winner !