And probably a longer line for the tap you want to serve a higher PSI beer out of, right? Otherwise, you'd get pretty foamy pours on that tap, I'm thinking.
I think this is an important point - if you want all of your beers to have the same CO2 level, then one secondary regulator for all of your kegs is no big deal. If you want to have different CO2 levels for different beers, you need a secondary regulator for each different psi setting.
The cheapest and easiest setup would be one CO2 bottle feeding a single output regulator, feeding a dual output manifold.I agree...this is the best way to go as long as you don't mind using the same psi for all your kegs
Yes, exactly, you need to balance each line in the system. If they are all on the same psi, same shanks, same taps, same line, same length. If you change the psi or one of the other variables then you need to recalculate. Higher psi means longer lines, all other things being equal.