you'll hit ~73% crit without highlords and ~83% with it (+6% overall relative dps to everything)
whereas with pride merc setup you might have ~1850% ed with loh, ~1500% without (+22% overall dps to demons)
And that 50% fire resist is pretty nice, +30% cold resist is not
that's besides the +1 all skills boosting overall dps by whatever margin, the LoH setup clearly wins out but requires a rare fcr diadem and crafted ammy hence its not simple
your calculations are accurate, but it definitely depends on where you are going to be farming. given that there are demons, undead, and animal types, if you assume that 1/3 are demons, it is true that doing 22% more to demons will yield on average 7.3% more damage overall statistically versus +6% from crit. but as you can see, even so its only about a 1% difference assuming you are in an area where demons are clearly 1/3. If you go to cows, for example, none are demon, so the LOH is not useful at all, where as in chaos, you may get closer to 1/3 demons, giving you teh 1% edge
that is on top if what you stated which is that you need to find a GG +2 lock ammy with +10-15 FCR, which at this point is very hard to come by