Very good and interesting variation. At least using Tequila blanco I would suggest to up the punch liqueur and even possibly add a bit sugar syrup. As in every Margarita some salt solution helps additional lifting the flavours.
I live in San Diego, so we have tasted lots of different margaritas. Tried this one as we just got some Swedish Punsch. It was outstanding. Has that typical margarita taste, but with the added flavours of the Swedish Punsch. All work well together and produce a cocktail that is way too easy to drink.
This is an outstanding version of a margarita (go ahead and salt that rim if you like). Kudos to Simon for thinking to sub Curaçao with Swedish Punsch. It complements reposado in a wonderful way. No sweetener necessary.