I have not heard the specific model of ProAc speaker you are looking at, but, I've heard several other models, including stand-mounted speakers with the ribbon tweeter. I really like the ProAc ribbon tweeter speakers I've heard. This is one of the rare brands that successfully pull off the integration of a ribbon tweeter with conventional dynamic drivers--there does not seem to be an obvious difference in the character of the sound above and below the crossover point.
Because the K-1 has a dedicated stand, to me, it is really not that much different from a smaller floor-standing speaker, so I don't know why you have ruled out floor-standing speakers. But, I will note that several years ago, I heard a stand-mounted ProAc (I believe it was the D2R) and another ProAc speaker with what looked like the same drivers in a floor-standing configuration; the stand-mounted speaker being cheaper in price. I liked the stand-mounted speaker more, and the dealer noted that, when you added in the price of a good stand, the two models were comparably priced.