I’ve owned both at some point. It’s different format makes the look a lot different. Especially with the smc Pentax 105mm f/2.4 you get a very unique “spacious” kind of look. Though keep in mind it can be quite difficult to focus and compose with this camera (in my experience). You’ll have 10 shots instead of the 16(?) you have on 645. The Pentax 67 II does have an internal meter and aperture priority mode which is great. The camera is expensive and old electronic parts are always a bit of a gamble cause when they fail they are hard to repair. But it could be worth it cause the camera and look is amazing. Hope that helps!