Well, if you have full information about your opponent then the result would be exactly what you don't want - spending essence (although I imagine it would require mana, not essence) to counter a spell. And if you don't know, then it puts the defender at a huge disadvantage because you're relegated to either your opponent's spell go through unchallenged, or randomly guess and risk screwing yourself even more. I'd prefer a straight-up "spend mana to counter" system, although I'd prefer even more a system where different counterspells would function better against certain types of spells (some might specialize in dispelling enchantments, some against blocking or dissipating direct damage, etc). You could also throw in a mechanic whereby the type of mana you use to power your counterspell affects the outcome, but in a way totally transparent to the player. For example, you might be more effective at blocking your opponent's volcano spell if you predominantly power your counterspell with earth mana; water and fire could be a bit less effective and air even less. But, to keep things from being too much in favor of the offender, mixing water and air might be just as effective as using pure earth magic, etc.

But the effort required to gather full information makes it different than a pure mana for results scheme. It does put the defender at a huge disadvantage against an opponent they're unaware of, but I don't feel that to be a bad thing. If a channeller gets to the point of being able to cast a devestating spell against your forces, and you're unaware of it, then you probably deserve the results of a sneak attack! They're usually more damaging in D&D for a reason.

I do like the concept of varying counterspells, which is what I was trying to get at earlier. Making different styles of mana have different effects on spells is something that I do like conceptually. I could support your example at the end.

I'm fine with having information about your opponent allowing you to 'fine-tune' your counterspell to make it more effective (although honestly, I don't see the advantage of having to manually move sliders or whatnot if the game tells me what to do anyway - it may as well automatically factor in your info and go from there...). I'm not fine with having to randomly guess at how to 'brew' your counterspell if you don't have good information - resulting in anything from complete success to making yourself even worse off than if you had done nothing. Too much randomness in something that could make or break the results of the match...

If you're interested in considering things like "dampening the winds of the flow of essence" around the channeler, you will probably have to resort to imagination. Which is not a bad thing...