I found a real good deal in some fks 180s. The only problem is I set my din about 8 and that's the minimum. I could also get done sth 12 drivers for the same price but I've heard the fks are a better binding. Plus k for help.
If you're riding at a 7.5, realistically, you'd be fine with 10 DIN bindings, assuming you're not going to put them much higher. Anything more is kinda overkill, but the higher the DIN, a lot of the times means a higher quality and more durable binding.
IF you found a good deal on them, then yes get them, assuming it's like the same price as these others you're looking at. it's an 8-18 so you'll be set for life.
If you're riding at and 8 and describe yourself as an intermediate park skier, then I would say that that and 18 DIN turntable is indeed too much binding. While I love the FKS/Pivot, the STH/FFG series is my next favorite binding as both a skier and a ski tech. Whether you get the 12 or the 14 DIN version, make sure it is the driver featuring the driver toe. You don't want any of the Z toe wing release crap. The driver toe is a sold, durable, reliable to piece. I would go the Salomon route, I doubt you'll be disappointed.
He'd be ok with a 10 din based on the spring only, i wouldnt trust z10s to hold me in even though im in their range. He'd also be fine with an 8-18 din binding.
Im at 7.5 and bought px15s because i wanted the metal driver toe. I had to turn my din up to 8, the minimum on the binding. Ive also been skiing harder this year to justify the beffier bindings. As long as hes in the din range he will be just fine.
I get that he will never use the majority of the din range but that doesnt matter. Most of us never come close to maxing out our din though.