GX680 is an excellent platform for film. The large image size and the perspective control are very unique compared to other MF platforms. Be warned through, if you want to use it for digital.
Like other cameras without geared control, you need a very good skill for precise manipulation. It's very possible you don't. You might find the focusing is never right. due to the lens design, you could also find unacceptable color shifting and light fall-off in the edge. Digital backs without micro-lenses could help. Of course, you can also use SW to correct it. But that's not the same if compared to the lenses designed for digital.
One thing for sure, you'll like it to be in you backpack. I can assue you it helps to build a strong back,