I think the EC and MC version are the best, for channeling use the EC version. But, as SOHK says, they should be adjusted to evade abuse or overpowering it.
I like the idea of using the user level from SOHK, so I usually use the skill as EC says but with changes:
- Use the user level instead the magic ritual ranks to determine the difficulty.
- You need the same ranks (or more of course) in magic ritual than the level of the spell you want to cast.
- I usually don't allow to cast other realm spells. Maybe only if the skills for those rituals are restricted (for ALL, independent if skill is originally everyman, that is only for own realm ritual skills), and using the EC penalties.
If a non-spell users wants to do a magic ritual, it needs PP, so it must develop the ritual skill and the PP skill.
The use of various ritualists can be used to add level, usually it should be added half the levels of other ritualist, as you add half the other levels of spells combined in ritual (EC rules).
This is for essence/channeling that use the EC rules, for mentalism I see correct the MC rules, because it can be powerfull, but at the same time dangerous, failures have a high price to pay from ritualists.