Help a newbie learn the difference between the classes

[Crevox]

Right now, the way I see it is that a 8-man raiding group should have a SCH, with the 2nd slot being either WHM or AST.

The group should have a WHM, and then the second slot should be SCH or AST. SCH is really strong right now, but either way, you really really should have a WHM because it's the only source of the MND party buff.

[Tranquil]

either way, you really really should have a WHM because it's the only source of the MND party buff.

I don't really follow this kind of thinking. Having your heals splash for a tiny bit higher per cast (3%) is highly inconsequental if the job can otherwise be done. We don't maximize our pure-HPS throughput in the same way we maximize DPS. (It hurts our off-DPS very, very little to not have a MND buff, but only 3% at most - and that is also assuming we have 100% DPS-uptime, which we won't whilst pushing progression).

It's a factor when considering WHM having a slot, though. Also, I don't think any healer is downright underpowered right now, but I do think SCH has the most to offer. I honestly foresee most people either running the old SCH/WHM or then going for SCH/AST, especially if they tweak the latter a little bit and also have the new fights not require that much continuous burst-healing galore, after you've gotten the hang of the script of a fight.