When you order your camera, give Richard a call and talk to him about your future plans. Richard will tell you if you are thinking of a size larger than 7x17 in the future, to order that size now with a 7x17 reducing back. This will save you the cost of another bellows. While a 12x20 bellows can be used with a 7x17 back, a 7x17 bellows CAN NOT be used with a 12x20 back!
I own a Ritter 7x17 and just love it. You will not be sorry you decided on a Ritter camera. As a matter of fact, I like my 7x17 so much that I have also ordered one of Richard's new 8x10 Carbon Fiber Cameras. That will lighten my 8x10 kit by about 6 lbs. :-)