Congratulations on dropping the age limit in your competition; I hope this is something other organizers will come to their senses and emulate.
I would like to to ask two questions, first a quasi-semantic one: How important a role will the sound/simulation quality of the mock-up entry play in the selection for the finals? That is, are you really looking for the best composers, or the best programmers? Great big difference! In my humble opinion, if an aural simulation of the score is required for a Composition competition, a simple rendering of the Sibelius/Finale Play engines should be more than adequate these days. After all, a score will be provided, and the non-musician members of the jury perhaps should not have a say - or have less of a say at least, in the 1st Round of selection, and subsequently, only after they have heard the selected works played by an orchestra.
Remember, a lot of token dime-a-billion self-proclaimed composers out there can provide you with a decent virtual rendering of their banal, derivative and unoriginal sounds. Perhaps the next Williams or Morricone cannot, since they are spending most of their time bettering their art, rather than learning more software than they have to, or spending whatever money they have buying self-composing libraries.
Are you looking for the best all-rounder maybe? Then this should be clearly stated. It depends on whom you are after and spending your money to find... But, again in my humble opinion, it should be much more important to discern and give voice to the best artist out there - after all, they can always get programming assistants when they get a contract - that will give us glorious music again in film, rather than the jack of all trades; you don't need a competition for that, they are all around us. It would be such a crime to miss out on a truly gifted musician, only to reward somebody for riding the Mod. wheel better - i.e. the better engineer, or merely the owner of a better studio (again, engineer).
And the second question: Who are the jury this year?
Best of luck, and again congratulations on organizing this competition.