Paradigm 3f vs 120h

Blade and persona with my Hegel h360 driving them are quite different in presentation with the soundstage and imaging being much larger thru the blades, but the appeal of the persona's was that pinpoint imaging so both excellent in the way they get it done. The dual 8 1/4 woofers of the persona are maybe the best in the business tho' and now that I've upgraded my hegel to the h590 the blades might be as tight, but I don't have them to compare anymore. The best results with the persona is with them along the long wall and your Krell should be great. If I could undo the deal that got me the blades I wouldn't but that's not a knock on the persona 7f, more like I had the kef R105/3 for 25 years making the blades tone familiar. TBH both speakers probably sound better than i'll ever get out of them.

The persona’s have a much higher ceiling with superior detail, resolution, and soundstaging, but need more tlc. You can stick the founders into the corners and point them at the listening position and jam.

I listened to the 7f at the dealer for a year b4 buying them and they were so sensitive to components! They were the only speakers I could reliably hear a difference between dac's. I also noticed when the speakers were moved into a room that had a tv monitor off to the side but within a few feet and I heard some midrange glare from the reflected sound. I loved them with the pathos logos mk2 but not so much with my hegel h360. 

If you have room from the sidewalls you should be fine. I had a pair of blades come up locally I wanted to try so sold the persona's. If your room is small the 7f is probably more bass than you need, the 3f can fill a room with tight deep bass and you can eq the drivers all you want they're bulletproof.

The 120 likely will throw a larger stage, the persona'a present a tighter picture

I have AT’s back here, the 120 will boogie and don’t do anything wrong. The persona’s get a bad rap because they’re very sensitive to component matching and placement, but having spent so much time with the persona 7f in different rooms and with different components I would recommend them on the condition that you either know how to set up a system or have a dealer familiar with the line that will tell you what you need to make them sing. The f120 is easier to get good sound from but have a lower ceiling. 
 

In my current system even with the same music every listen is a revelation, I think the persona’s have that ability also while the founder line is less refined.