I currently work for a short run book printed and the KM1 is a good fit for us. It's used in conjunction with a digital 4/4 web and digital 1/1 web and single toner based machine.
It's like any other piece of equipment, as long as it makes you money it's great.
My only gripe is that from a prepress perspective the RIP is not great. I wish the DFE were more robust. It's chocked on jobs that I can send to a an older Fiery without an issue.