I have participated in a few mix contests and they end up for the most part being popularity contests. Whoever gets the most votes while listening too and commenting on a set number of others mixes ends up winning.

Most have very little to do with the actual ability to mix a pro sounding mix.

I had a conversation in the sonar forum with one of the judges in one of the contests. He is a well respected poster over there. He had serious disagreements with the other judges over the top 10 mixes over the technical aspects and swore he'd never judge on that website again.

If you want to grab the stems and mix for your own enjoyment, by all means do that. Heck, even post them in the contest if you want. You might get some worthwhile feedback. Who knows, you might even win.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.