It's really hard to have an overclocking competition that's 100% fair to all the hardware possibilities out there. I actually ended up buying a UD5, just so I could play in this competition. Will I win a board, probably not (someone using LN2 will probably kill my scores LMAO), but even if I did it wouldn't make much sense, for practical purposes, to have a UD7 over a UD5, or even a UD7 over a UD3 Unless you really needed the extra PCIe slots.
Even % increase competitions can be very flawed.
What it comes down to is if you've got the required hardware and want to enter the competition enter it. If you don't have the hardware, overclock what you've got and just have fun anyway.
There's no sense in complaining that the people who spent more money on there hardware have.., better hardware.