In the past, I have used round metal and nonmetallic plaster rings on 4-square and nail-on ceiling boxes respectively for supporting light fixtures before the 2008 NEC without issue, but I am no longer sure if this is an approved use for these plaster rings.
Are they now relegated to use for wall mount fixtures and utilization equipment under 6-pounds?
Do these meet the requirements of 314.27[A] when used with new work ceiling boxes?
I can't seem to find any direct reference in the NEC regarding the use of these with a ceiling box when used for lumunaire support.
The UL white book only seems to mention box extensions and device boxes with plaster rings similar to the exception to 314.27[A], but nothing about plaster rings used with ceiling boxes for luminarie support. The rings themselves don't have much info on them either other than Cu. In. and UL listing.

314.20 passively mentions setback of plaster rings in walls and ceilings, but that is all.

314.27[E] refers back to 314.27[A] and the exception to 314.27[E] simply mentions plaster rings only on boxes used for support on Utilization Equipment under 6-pounds, which as I understand refers to things like smoke detectors, occupancy sensors, etc.

TKX