I reached out to a few op's who were routing a DI when I was considering it. The typical feedback I got was that they were earning about what a Stern makes, give or take. ROI is exactly what I was thinking about as well. I decided that I wasn't going to get a DI at that point. I like the game and maybe some day it will come down enough for me to get one.
I look at it this way, what am I trying to do with my route? I see there being two paths. Am I trying to grow (locations or game count) or am I at a good level and want to up my overall game level? Tucson Pinball is still growing, and I expect with 1-2 locations with 8 total games more and we would be at a point that we just want to maintain and upgrade games over time. We recently added a 4-game location and I was looking at it like I could get 4 games (system 11's or classic Bally) for as much as 1 Stern. That's recently changed so I can't get all 4 for a single stern, but at the time that was a valid comparison.
JJP games, for now, are just too much for just earning about the same as a new stern. When we max out on games, then yes, I expect to sell 2/3/4 games and get a single higher level game, but that's probably still a year or two away from considering that.