I owned a North Jaime 138 last summer. Monarch isn't too harsh on my knees, no worse than the Jaime or my Carved Imperator 6. Toby is correct too, comfy pads make a difference. SP QSR and Msr pads are my go to.
Liked the Apex bindings, but I prefer the ratchet to the velcro when having to go from bare feet to boots back and forth.
I would have probably bought the KL Pro if they did it in the 135.... Both graphics are fine, but I prefer the 5cm G10 fins that come with the KL. I did manage to score some 5cm Naish G10 fins.
(huge thanks to Angelina at Naish USA!)