Having read most of this thread, I've found it all very interesting. Now, I feel like throwing in my two-cents.

I think many are trying to match the vest with the coat instead of the vest with the tie and shirt. I think the whole reason this model is shown wearing a 5-button vest/waistcoat with a Prince Charlie coatee is because of the tie he is wearing. Call it a cravat or rusche tie--I personally think it's too messy for a cravat--it would look weird untucked as it would be with a three-button vest.
The three button vest really goes with the bow-tie. This is the classic look for formal and semi-formal wear--and the three button vest also shows off the studs the generally accompany the pleated tuxedo shirt. (I think that one ought to invest the pittance it costs to get some studs for the tux-shirt as it makes it look so much "smarter").

I am not a fan of the Prince Charlie (or the three-button vest)--I don't find the cut particularly flattering on gents unless they are slimmer than the average. I prefer to take my Argyle jackets and dress them up with tuxedo-wear as I think they look better on more people. Of course however, I adore the doublets we see: Montrose, Kenmore, Sheriffmuir, Regulation, etc.

Anyway, I also tire of the "sea of black" jackets that someone earlier mentioned. Obviously, they are easier to match and bulk produce, but shouldn't be striking out to make a statement with something other than a kilt? ;-)