We almost always leave the grindings. We always rake them up and leave a neat pile. The customer is ALWAYS told there will be a pile, sometimes quite larger. Cleaning them up isn't bad if we can get a skid steer to the pile. We have hauled them away and put in topsoil, a few times we have laid sod down also. The largest stump we did was a silver maple stump. We bought a ms880 with a 60" bar to flush the stump, had to hit it from both sides. We still have the stump, it's at least 7' at it's widest point. It took an 8 hour day to grind it and clean it up, it could only be flushed about 2' above grade with the flare rock at the base, surrounded by a driveway. It filled a F-550 stakebody with 3' side and 20' long bed at least twice. I have pictures of the stump, I need to try and post them.
I have ground stumps for another "tree service" since he doesn't have a grinder. He said grind 4" below grade, load the grinder and go, it didn't feel right doing that half a$$ a job. No clean up or anything, I was glad we were towing the chipper with his truck so our name wasn't associated with the crappy job.
I ground my neighbors stump, they put trash bags with grindings out every trash day for a few weeks and got rid of the grindings that way.