Because of my limited need for such a camera, I have fixed a budget of USD2,300 for one with a 105mm lens.If that is your circumstance, look for a Fuji G17 instead of a GX617. The G617 uses the same lens but it is part and parcel of the body as is the finder. You'll want a center weighted filter as well. If you cannot find the Fuji, I used to use a Heliopan 1.5x CWF with mine. The Filter diameter is 82mm. If you have a choice of more than one G617 shoot sample shots with each. My G617 was terrific but I've read reports from others which were not so laudatory.
When I started looking for an interchangable lens 6x17cm camera I decided to go with a (no long discontinued as the maker is dead) Hanchett V-Pan Mark III (
http://www.igorcamera.com/panoramic.htm and
http://www.cameraeccentric.com/html/info/vpan_1.html - iam not associated with either site) as it offered shift (vertical and horizontal) , tilt and swing - but only on the lens standard , could focus infinitely close (interchangable bellows and additional rails), and could use lenses from 72mm to as long as are made ( I used lenses from the 72mm Schneider Super-Angulon XL to the 720mm Nikkor-T).
If I were looking for a newer camera with rear movements I'd look at the Canham 5x7 MQC body (
http://www.canhamcameras.com/5x7.htm) combined with Keith's 6x17cm rollfilm back (
http://www.canhamcameras.com/Roll%20film%20back.html)
Despite of it's versatility, with one exception, the 6x17cm format photos that continue to make the most money for me as stock photos were shot with the G617. Simplicity has its merits.