Dilemma Slick SLS / New Slick

I started learning wing foil last year, Greece island Karpathos. My first wing was old Slick 4.5m. I quickly learned how to foil and become addicted. My board is still KT 105l, for this summer I change foil to north sonar MA 1200 and 1350. And added Slick SLS 3.5 and 5.5. I can make firs flying jibes

on new foil. New North Seek board 78l is on the way. (I am 70kg, 60yr)
New Slick SLS wings are amazing. Great wind range and also upwind for me. IMHO better handling than old Slick. So I want to sell old Slick and buy new one same size. BTW same price for Slick SLS or new Slick in my shop.
What will be your choice, recommendation ? Who of you have experience with Slick SLS and Slick what is your favourite and why.
Thanks, Ivan.