This maybe due to MA not actual mdam, limo my SS will land 45k-62k on mobs, but I have 37k ma, im well beyond the ma soft cap for the trash mobs, therefore I crit more.
With that said Vhatos affect mdam, so if your ma is lower then the mobs mdef all the mdam in the world won't make a difference. Warlock is such a heavy MA/Int build, you really have to sacrifice health, but that's another topic.
This is actually incorrect. If your damage goes up you will hit for more on any mob you can hit period (if you compare apples to apples, ie average non-crits).
Extra mdam is ALWAYS beneficial in every context. However, there are circumstances when more ma or crit will be MORE beneficial, which is why Vahtos is no longer the preferred caster accessory set, despite the fact that it still has the highest magic power bonus in game.
No matter how low your ma is, if your mdam goes up, and you can actually hit the mob (if it's too much higher than you are you'll miss), you'll do more damage, even if the increase is small. Depending on how close you are to the ma threshold of the mob (say it has 120k mdef and you have 100k ma) ma food may make a much bigger difference in how hard you hit. But the relationship of mdam is static in the sense that it's a fixed value. As it goes up, your damage goes up.
Ok, back to actual topic: Warpro, I think more testing needs to be done, and you might want to pm Pazuzzu, cause he's the US-side caster damage testing expert. If anyone could help you figure out how Warlock damage is calculated, it would be him. Bad thing is, he doesn't have a handy shrimplet on Osha to test on that I know of, so you might need him to come over to Palenque to help, but if you ask nice enough he might. Numbers are like crack to him.