Do they last their rated hours or are these junk lamps?

I don't know about their PSMH but Lumapro's T8 fluorescents  are trash ! They buy them at work 'cause they're cheap . They suck !

Not sure but odds are, they source their lamps from the same Chinese factory/factories that many other companies get their lamps from.

Considering stocking up on them? I was thinking the same thing to be honest. I don't know how they are in terms of lifespan but I have a Plusrite 70w mogul base lamp and it has really good light quality and seems to be well made.