Just pulled the top end off my 44U Bobber big twin last week, one of my valve stem oil seals had worked loose, so I took a look inside. After 8 K miles, cylinders show no visible wear, pistons look great as well. I had just returned from the annual trek to Rhinebeck, then Worchester Mass to see my son. A 700 mile weekend, no noticeable oil consumption via the dip stick. The return trip was via the turnpike/thruway, kept it down to 63-65, no use in pushing too hard
I'm willing to say at this point that adding extra oil to the bottom of the pistons via the oilers I've installed definitely seems to prolong engine life.
I also noticed that the "hot spot" on the edge of the piston near the intake valve area has gone away since I've stroked it and thereby created about .030" popup into the cylinder head. I, of course, milled the head to accommodate.
I'm guessing the nature of the gas burn has been changed as a result, moving or eliminating that hot spot.
Just thought I'd pass on what I consider good news to those who have considered or are undertaking these modifications.
Sorry I didn't have my mics last weekend to give specific data, loaned them out to a friend, but eyeball inspection looks good, and the motor definitely does not have any piston slap