Thank you for your input, and it's not a bad idea at all; the only possible problem I can think of it, is that many people's SBD balance will be zero, especially if you're new, so that would be a different (and probably worse) kind of exclusion.

The next one I'm running (as with most of them) will have a 7 day time limit, so that at least gives people a chance to catch the comp. Also I always try and get entrants to resteem to try and spread the word, lastly I've seen a few good services that detail each and every Steemit competition each week, and so I've finally been included. Hopefully all that will mean more entrants; I got more than ever before to my Animal Head Challenge, so much so that I gave out 4 extra prizes! :0)

Cg