The G2L first came out with the plastic bezel then surefire switched over to Al because of heat and regulation issues. I can't tell you whether they have had a revision to the led in the P60L. I think it has always been the same, but I could be wrong.
I don't believe I'm aware of a G2L-YL without its aluminium bezel. Only the G2L-BK's were first released without.
Note that the revision number in the manual is for the instruction manual which is not always updated at the same time (if ever) when the product is evolved.
In this case it would be interesting to check whether the revision numbers of the instruction manuals are different [and it they relate to different versions of the G2L's]
not sure if this is considered a revision but as most are aware they also changed from the smooth reflector with frosted lens to a textured reflector and clear lens..
I thought both the -BK and -YL G2Ls were both originally released (at the same time) with the nitrolon heads The G2L-YL was updated to aluminium later than the G2L-BK.
At the time a lot of CPFers seemed to be wondering if they could get a yellow aluminium bezel for their nitrolon G2Ls if they contacted SureFire, as people had been successful in getting aluminium replacement bezels for their G2L-BKs.