Sorry to hear this, Aeros. You know some of what I have gone through with my Pentax service history.
I firmly believe Ricoh needs to offer a seriously uprated "pro" level of service and support for the 645 system, and I've been pretty vocal about that in various forums... but more importantly through my local dealer (a highly respected professional shop that has carried Pentax forever) as well as face-to-face with the Pentax rep.
IMO, a $600 repair bill for impact damage on a $5000 lens is not out of line. I know from experience that Canon, Nikon, Sigma and others are charging repair fees like this on 35mm lenses that are much lower priced and sold in much higher volumes. You may choose to pay it or not, that's up to you. I don't consider the cost to be gouging but recognize that each person will place their own value on such things.
More troublesome is the lack of responsiveness, communication and timeliness in the servicing. That, to me, is what's unacceptable about your experience. My 10-week shutter replacement trips to Japan with no loaner program, etc., are already at the outside of what I'm looking for in a camera system of this level. Your 4+ month wait for zero results blows way past that. Totally not acceptable!
You've been a Pentax shooter for a long time, far longer than me, but either way I agree with you that the system is fantastic. I would encourage you not to bail out of anger, but stick with the rest of us in trying to influence Ricoh to bring this system to a truly professional level of service and support. Ricoh is fully capable of doing so, and where else are you likely to get a digital system with this level of bang-for-buck? The trouble is like any large company, Ricoh's focus is diverted in many directions. The camera operation is a tiny fly-speck of revenue, plus no doubt there's constant nagging about the bottom line since the economy still pretty much sucks. So the issue for us is that change probably must come from "squeaky wheel" attention and some much-needed market success. We need to be the squeaky wheel, but not in a scorched-earth way. If Ricoh thinks there's no upside to increasing their level of support, because everyone is just going to burn them to the ground on the first bad experience, it may not create the outcome we actually want. And that is for the camera system to get the level of support it deserves and succeed in the market.