Hales T5's Vifa's $ ohm or 6 ohm?

Sean is very explicit BUT, things aren't that complicated since: you've worked on the x-over so you know (or the modder should know) the tweeter schematic. You can test the existing tweeter(s) to get the parametres & impedance/ amplitude curves OR, simply, back-calculate the "ideal" tweeter parametres based on the tweet's cross-over...

The only thing you CANNOT do, I guess, is actually listen to a bunch of tweets to decide for yourself. Take a look at the LDSG for a few ideas. You don't need to hurry!!
Cheers.

Oooops just remembered the "killer" Vifa tweet fm their XT series. It's the 25TG30-04 (4 ohm, as indicated).