Nathan,
According to EVERY teams PIO, all the teams now use a vegetable based oil in their smoke systems to cut down on pollution (while burning that 'green' oil in the exhaust of Jet A or JP

. I can't calculate how a few ounces of colored dye in the mix would cut down on smoke time since no teams (and very few individual performers) leave the smoke on for the entire performance. As far as mixing the stuff, if you are the Blues or Birds you have the FNG doing all the mixing and pouring until the next FNG joins the team and it becomes his job, and if your team is doing 3 shows a week plus practices, I'll bet you'd get really good @ pouring that stuff and not losing a drop.
I'm more interested in making the presentation more interesting, If you've seen the REDS, PDF, or the Italians shows, the first thing that gets your attention and holds it is the different colored smoke and how it all blends into itself and how it makes it easier to see what they're doing during complex maneuvers like cross-overs.
And if you are the guy with all the lightening bolts and farts and darts on your suit, you should be smart enough to figure out you could possibly ruin your fancy duds, or have an aide who whispers in your shell like ear about the possibility.
And, for a reference point, the first time I saw the Blues they were flying straight winged aircraft called F9F-2 PANTHERS @ NAS Sand Point.