Interesting.
Hope that we could really have a compilation of accounts on introducing tangs. It's interesting that a play on two factors (great size difference and introduction of multiple tangs at the same time; and maybe a little luck) would probably account for the success of the situation.
One thing I also noticed whether it be angels or tangs, they grow quite fast when they're "catching up" to the size of other fish, but relatively slow when they're just growing for the sake of growing in size (I believe there are exceptions to this like the French angel and the like). My PBT has also caught up in size with my Mustard Tang in just a span of 2-3 months, after that, I see no growth in my Annularis angel, mustard tang, purple tang, or even my PBT.