I noticed your contest did not have a lot of entries yet, so I figured I would give another designer's perspective on your ideas. Here is a crest/emblem logo for your consideration. I implemented the Camo/boot camp feel, while still keeping "A Cappella" in a separate, rhythmic font. I also incorporated "ABC" into the design, as I think it is a great acronym and should be visible on your logo.
Let me know if you would like to see any changes or variations on this, and I will be happy to provide. (I will be on here a lot between now and the end of your contest, allowing for quick revisions, if needed.)