I just think the idea is flawed. A lot of people only have a liimited amount of time to play when they log in, limiting how often they can launch I don't think is a good thing. I tend to measure my fun in an evening as a quest to get in as many fights per hour as I can most of the time, anything that limits that I don't see as a good idea.
I just think it's better to have more planes in the air to oppose people rather than programmatically limiting the number of targets.
Something just popped into my head though...
What if instead of the person clicking on the low-ENY plane and being told they have to wait for x amount of time, instead maybe they could only up low ENY planes every so often, and limit it that way?
So for example, say I log in for the evening, ENY's 20. I say to myself, 'Hey! I wanna up a P51D because it's the bestest!' I up my pony. I fly around, doing my thing, eventually get killed. I go to up it again. The system comes back with, 'Due to ENY restrictions, you can't up a plane with less than 20 ENY for another 45 minutes.' (specific timeouts I'm just pulling out of my backside) And that 45 minutes starts when you end flight. But, you can up anything over 20 ENY at any time while that runs out.
Now say I log in for the evening, ENY's 10. I up my pony, the flight ends, and I'm allowed to reup something with less than 10 ENY in 15 minutes. Less time for less ENY difference. I'd get the same timeout if ENY was 20 and I upped an ENY 15 plane.
Basically it would allow people to take up the good stuff once in a while, but doesn't limit how often they can fly something.
Not quite sure how it would be a substantial improvement over the current situation though.
Honestly, I'd be curious to see what happens if ENY gets ridiculously high and Drediock's idea was used. Take the plane that is statistically flown the most by people who aren't in squads or groups and disable it for that side, so if you want to fly it you've got to switch. It would be interesting, I think.
Wiley.