WP 5.1 vs WP7

Gentlemen,

I have decided that I want a pair of Wilson Audio Specialities Watt/Puppies. I have been wanting them for years, but...
My budget does not allow me to buy new, so 2nd hand here we come.

The question is if the WP7 is worth 2/3 more than the WP5.1. The 7's I have on hand are (according to the dealer) mint with all accessories and Fly Yellow. The 5.1's have had the midrange changed (by authorized distributor) and have usual used item marks, but fully functional and standard black.

I lean towards spending the extra money and get the 7 - which I can have at very good price, probably due to the color (Fly Yellow). I will go course also have to live with that color in my living room for an extended amount of time :)

How big are the sonic differences? I am told that the 5.1 are hard in the top end - not really something I have noticed when listening to them, but then again I didn't listen with the intend to buy. I have only briefly heard the 7's here and there.

Thanks for your comments

Henrik