If the next contest doesn't involve 5cp maps, I WILL KILL EVERYONE FOR ALL TIMES EVER!
I probably wouldn't even enter, but competitive players need new mappers desperately. This Koth contest is great, but 5cps are really the bread and butter of 6v6.
You have to realize that your pug testing group is probably the last bastion for reliable map feedback and testing for mappers who aren't competitive players themselves. It's an amazing group, and without it all hope would be lost, seriously.
A established mapper or competitive player turned mapper could probably with some work get a comp-ish map done, but as we know there never exists more than like 5 of these people in total, at any given time. And out of those 5, only one map might get some real playtime for half a year. Then it's killed for not being badlands.
Starting a 5cp competition wouldn't change much, I doubt you'd see many comp worthy maps come out of it. Mainly because your testing group wouldn't be able to handle ALL the testing for every iteration of every map in a 6v6 environment, there needs to be more (in quantity) supportive players and testers. But the current support a unknown mapper gets from the average comp player/community is non-existent and in some cases it's even negative.
Supporting a mapper is not about shoving endless praise at them, it's about giving feedback, and it IS possible to disagree with a design decision without being a dick about it, which is something most comp communities seem to have misunderstood.
Basically, the comp scene doesn't look that desperate for new maps. As they (generalization ahoy!) keep on demoralizing or ignoring any mappers who dare attempt competitive scene mapping.
Unless of course there's a massive silent majority of "new-map-supporters" in the comp scene that no one has seen or heard of... If they're there, and desperate, they seriously need start showing themselves. Because the new-map-haters are currently winning (and have been winning for the past 5 years).