Interesting that the larger chamber I'm looking at is 18G, the math says that the target mist interval should be ~.33 seconds with two of the Tefen red CV misters. What misters were you using, how were they placed and what kind of coverage were you getting?
In a 5G bucket the math says ~.09 seconds with two Tefen red CV Misters. So it MIGHT be doable with a single mister if you're willing to risk losing a girl for a clogged nozzel.
I am not totally positive, but I think nozzle clogs can pretty much be eliminated by using good non-organic nutes and a small micron filter. If you're really paranoid, you could always switch the nozzles out and soak them every week or so- since you only have a couple at most. The other issue though is adequate coverage- not sure if a single nozzle will accomplish this or not in the bucket.
I haven't said which misters I'm using, they are the Tefen red CV, 80 degree conical pattern with rated flows of .040, .048 and .062 liters/min. at 3,4 & 6 Bar. I haven't wanted to overrun your thread with a detailed description of my system as that should be in a separate thread, and will be as soon as I get the electrical routed.
This was handy http://convert-to.com/485/flow-units-converter.html for converting my nozzles that are rated >.04 oz/sec @80-100psi to your litre per minute rating. At the higher pressures they are probably pretty close. Do you know what pressure you plan to run at, and will you be using a regulator to keep the pressure constant? It's ok man, if were going to talk about your setup, we need the details I suppose, plus it's totally on topic other than it's not my build- but I don't care man 
I was never trying to say that the buckets were the perfect solution just that they fit very well into a cabinet. I knew I would be over-misting, just not by how much. It is 10x not 50x BTW. Why would I have to recirculate? Even with a 1 second spray I should be under half a Gal per day, that's easily handled by the waste capture system in the cabinet.
I'm not sure you'll know the exact amount of runoff yet due to so many unknowns in your timings and stuff, but you're right, it's a small system and not much to worry about.
I wouldn't say LPA since the acronym actually refers to the system pressure, I would say less that optimal HPA but we are really splitting hairs at that point.
Agreed! 
To me it's not just a quest for perfect HPA roots, I think I pointed out earlier that there are several reasons I was drawn to HPA, among the most important being reduced nutrient cost, reduced water usage, increased energy efficiency and lower noise. I still get all of that even if I don't get the perfect root hairs.
The way I understand it, without the fuzzy roots, you will have to run higher ec as the roots are not as efficient without the fuzz, now were really getting out of my knowledge here too, as I've yet to ever have fuzzy roots myself YET... But everything else is valid points. Perhaps Atomizer will point out if I am wrong somewhere, or give any of his insight (not that I'm trying to sign him up for work)...
One of many things I considered, even some really crazy stuff while medicated, The issue I had with stacking buckets was that I'd lose another 14 inches of height, at some point you actually want room for the buds to grow. How tall is the cabinet you are planning?
The pressure switch actually doesn't run off any electricity, but only is a mechanical switch operated from the water pressure and I think a diaphram inside. I'm pretty sure the voltage listed was only a rating for the relay contacts it controls. 
... Anyway, your right as well about the mist- Atomizer once explained to me a big part of it was that the surface area of the drops caused alot of evaporation, which in turn really concentrated the nutes as they were floating about... 
