We don't have any curl problems with any of our Konicas (we have the 6501 and 8000 models).
As long as you are following the basics, i.e. keep good environmental control in the room the machines are in and always condition the paper for at least 24 hours before use, then I suspect your decurler isn't working properly and you need to get KM in to fix it.
Of course, paper with a low moisture content is best, but you state that you are using a digital specific paper. It might be worth using a different brand from a different paper merchant though, just so that you can eliminate that as a possibility.
You can switch the grain and I know that we had to do that with older digital machines, but the newer generations shouldn't need that. We switch grain direction based on the size and type of the product we're making and short grain doesn't exhibit any problems with curl (as long as the operator doesn't forget to set the decurler right for that job!). However, you might want to try long grain if you are really struggling.
Ripple is a different kettle of fish entirely and one that I haven't seen any 100% solution to.
We're shutting down the factory for the Christmas break in (counting down...) 2 hours, otherwise I'd post a picture of a couple of pallets of (flat) KM print that the print room normally has ready for the finishers.