From my experience i haven't noticed any premiums attached for OPC products vs Topps in the area of Nonsports cards.
I should qualify that i have seen higher prices on OPC Empire Strikes back full boxes and asking prices on all the Star Wars series too.
Even on the sports side it took a long time for collectors to appreciate the relative scarcity of OPC Baseball cards and only in the past few years have i noticed a significant uptick in prices on those cards..i suspect most of that is coming from those grading cards.
Also it doesn't seem to apply evenly to all years of OPC baseball.
Hockey is a different beast and OPC has always had higher prices.
I think two factors are in play here..One is the personal preference of collectors of Topps over OPC nonsports.
Secondly more discerning collectors appreciate the scarcity of OPC products and hope that in the future collectors/investors will too.
Just my humble opinion and i'm sure others cn chime in here and express their experiences with OPC Nonsports cards.