Are we talking about 'counterspelling' spells that are already active, or disrupting spells just after they're cast? I believe it makes a huge difference, going by the novels. I recall only one example when Harry is dispelling an ongoing spell and it is explained he needs to use the right amount of energy. Too much and the spells might explode spectacularly, too little and his expended energy would only fuel the spell and make it stronger.
It is your decision, of course, but this would mean that I would almost never allow a counterspell of an evocation just after its cast. You just don't know how much energy to throw at it. Even for an active spell, it is extremely difficult to gauge how much energy is needed to disrupt the spell, as you can only guess how much energy was put into it.
I can imagine using some form of spirit magic to cast out a 'net' of magic, designed to cut through and disperse magical energies that pass through it, but this would be more of a block or maneuver, if I'm right. Also, there's the difficulty of many types of magic only being magic during the casting: Harry's "Fuego!" spell usually ceases to be magical after casting and becomes normal fire.