I understand what Eagler wants, but I think that turning on the perk system would achieve a similar goal. I get tired of seeing Tempests, F4U-4's, and Spit 14's.
As for a rolling planeset on a permanent basis, I would be very much against it. Using myself as an example, let me explain why I think its a bad idea. Its no secret that the F6F is my favorite plane. With a rolling planeset, the current F6F that we have wouldn't be enabled until at least half-way through a month (more like the last ten days of the month) because it is an F6F-5, which didn't enter service until the second half of 1944 (last 3 months for it to see wide-spread service). Thoough I like the F4F and the F4U, I don't like them enough to justify time in AH when my favorite plane is not available. Give me an F6F-3, and then maybe we can talk.
What about fans of Russian planes? La5, La7, Yak-9U (maybe the -9T as well) were not introduced until well into the war. What do they fly until they get those? A rolling plane set could work, but there needs to be a much larger plane base so that everyone has equivalent planes to fly throughout the month.
Anyways, this is kind of a moot point, since the TOD arena will put planes into situations with historical context and against contemporary foes. The MA is the MA, and there is anything but historical match-ups and context in there.