At face value the quality of the photo is expected to outshine any other factors; that said, in order to encourage new members, and folks with less practice / experience, there are some opportunities here.
For example: Discern between very experienced / seasoned members, and beginners. For example you could have mini-comps that simply require the entrants have (a) never won a mini-comp before ( or have less than # wins), (b) or have under 100, or 500, etc.. posts (which assumes that the # of posts equates to experience level). This requires zero changes to how the site functions technically. Advantage is you don't have an Olympic sprinter going up against a high school track star, therefore I'd expect we'd draw out more members who otherwise would have been discouraged to participate.
I'd like to add that the moderators and members are very, very generous to share their time and experience, so change or no, the site is fantastic.