Well coincidentally, no one has ever pulled of a "regimental" formation, or even a battalion formation. They're all just a bunch of tiny, tiny companies running around, and calling themselves regiments. But enough of my ranting...
I'm from the earlier EPI(a founder) and obviously, I'd go with the platoons concept, especially because Prussians did historically operate their companies as multi-cooperative platoons in single formation.
You're definitely on the ball with these ideas, I would say. I'm pretty open-minded about this stuff, but maby that's because I'm experienced with that disciplined style of system, and after being in a couple of much less efficiency-minded and, pardon the insult, lazily-structured "regiments" at times, I know how awesome it is to have this level of structure! I think(or know) that folks that haven't been a part of such a system as this have an innate bias against it, thinking it's too difficult or simply not fun... how foolish they are.
The only problem I have with your "smaller than platoons" squads idea, is that we hardly have any "regiments" that can host enough men to even split into platoons, much less anything smaller. It's a good idea, but I don't think its very applicable to this community. Unless, of course, we had a huge boost in player count, which could happen with BCoF? It's a hope, if nothing else.
As far as me still ranting off-topic(because it's pointless and I feel like it), I'm still apposed to the stupid and absurdly inaccurate concept of calling a single band of 20-30 men an entire "regiment", which would, in reality, constitute thousands upon thousands of men in many companies, forming multiple battalions.
The many MM/NW regiments work as companies already, and operate in company formation, at least try too... I hope they try to... Anyway, I think it would be perfectly fine to call a band of men a "so-and-so" Company of the "so-and-so" Regiment, instead of the whole regiment itself. A couple of guys already went the more realistic path with starting their "company" for the future BCoF, but I see the miss-guided and completely pointless old tradition from MM caring over to BCoF. It's like me making a 4-man squad in Call of Duty/Battlefield/A-Battle-Game and calling it half the Russian army.
OH! And the original author of that image is commander Argus.