Hey Danny; I spent 10 years on series 2 Indigos. You didn't mention which series you run so I can only speak about the 5500 and 5600. I ran shells (that's how they refer to a digital press printing on pre-printed sheets) once a month. Usually 10,000 to 15,000 sheets, sometimes up to 20,000. The shells were printed on our 8 color U.V. continuous web offset press. No issues with the Indigo ink adhering to the substrate, but you should test first to be sure before you do this. The worst problem I had was because the shells for this job were printed on 80# gloss text. Normally no issue with that running through the Indigo, but with web presses like we have, the grain direction is always parallel to the web. These sheets were 11 x 18. So going through our web press they were grain long, but going through my Indigo they were grain short. Not a good thing to run thin paper grain short! Lots of problems with wrinkles. I was constantly adjusting the buckle to minimize this. But if you're on thicker paper, probably not an issue. And like I said, I tested this substrate before hand so I knew I was good on ink adhesion. I much prefer my current Ricoh ProC9100 to my Indigo, but I will admit the Indigo was faster running 1 click black. Also, I never printed over offset inks, always in an open area. I've also printed on shells from some of our non-UV presses on uncoated paper, usually 60# uncoated text and also no issues with ink adhesion. Your blanket life will probably go down and you'll have to change impression paper more often because it will really pick up the offset ink. Indigos offer a fast, cheap, black click so if you can get this to work it will probably be a benefit for you. Good luck and let us know how it works out.