Anyone knows the peak point of having Crit for SCH?

[kukurumei]

You really do have to take Eos/Selene into account. They make up for SCH's lower potency.
Plus SCH wasn't built to be a burst healer like WHM is. If they were, they'd be a WHM with a fairy, then nobody would take WHM to content. I think the devs did a great job balancing the 2 jobs without public testing. It's all about mitigating damage (boosting eHP in other words)

Eos matters even less since whatever increase the sch has eos has a fraction of that stat. So if a minor bump in sch, is a trival bump in eos.

It's just that in terms of stat choosing, very little can affect a sch like crit where a whm having more mnd and det directl translates into some more substance, because their have bigger multipliers.