I think this is a great thing you are pursuing!
My recommendation is to check out the Vifa D27TG - 45. You will have to check the specs, but it may be a drop in for your Vifa metal dome(don't want to get your hopes up). It is a 1" silk dome tweeter, with a very smooth, detailed sound. In my opinion, it will greatly improve the higher frequencies of your speakers. The cost is under $50 for the pair(if you don't find it, drop me an e - mail), and I have always felt that to beat this tweeter, one needed to step up to the very high end products such as Dynaudio, Hiquphon, Morel, or ScanSpeak(same company). I think this tweeter is the best bargain in the speaker hobby, and is used in many highly regarded audiophile speakers.
By upgrading to this tweeter, you would be running the same drivers as the Coincident Triumph from about the midbass up, since you already have the Vifa 6.5" midwoofer. The D27TG - 45 will lend you a much more smooth, refined sound, with great detail. A big improvement will be in the ease of sound, reducing listener fatigue dramatically. You will also notice that the speaker will sound as if you bought a more expensive replacement, now that you are hearing what a high end tweeter sounds like. You now will realize the idea of the PSB Gold, integrating an audiophile monitor with a subwoofer.
My feelings have always been the weak points of the PSB Gold are the low end of the high end metal dome Vifa tweeter, the crossover(has to be at this price point), and the very demanding load its partnering amplifier faces. You will be solving one of the problems.
I submit that if you are going down the road of upgrading the tweeter, wire, and binding posts, the benefits you reap will not be so great unless you also upgrade the crossover components. This will turn your 10% improvement into a 50+% improvement. If you are not into reengineering the crossover itself, simply swap out the current parts for a much better grade(not so hard). The improvements that SCR capacitors(same factory as Solen, but much better sound via thicker polypropylene/aluminum and higher DC rating) and North Creek or Alpha Core Goertz inductors will provide are phenomenal. Much more of a dramatic improvement than wire at, unless you are using cheap or very cheap, about the same cost. The crossover upgrade would be well under $100, maybe even far less. You don't really need to put money into the woofer crossover elements, you will see far less benefit there. Spend you money where it will make the most improvement, midrange/treble(which you are already attacking with the tweeter).
And, the cheapest method of improving a speaker's sound is to replace the harsh sounding OEM resistors with Ohmite wirewounds. This $5 - $15 easily sounds like $1000+ in the increased smoothness, air, and refinement. Really gets rid of a lot of nasties.
GOOD LUCK!