I can't think of a single CRPG that implemented the Vancian system well. Nor have I seen one mentioned in debates on this topic. Why is that?
TOEE did the Vancian system just fine. Usually you could not sleep in the temple without being attacked. Occasionally you would find a safe place to rest or you would have to risk it.
I think the Vancian system is a great in theory and can be amazing in practice as well. It makes players conserve their mage's powers and not just spam spells in a patterned succession. Further, it makes the player's plan ahead by memorizing the spells before the encounter, making it a gamble of what spells to take. This adds excitement and challenge to the spell selection. Do you take spells that allow flexibility for a variety of situations or spells with specific purposes? Do you go for raw Area of effect spells or single shot high damage spells? When you do get to that encounter if you didn't plan right it makes things exciting and fun, trying to make your spell selection work for the encounter or problem.
Further it allows diversity when creating spells. Spells can be the same level but one can allow flexability as the cost of raw power. For example: Spell Y can have more flexibility, as in, it allows you to summon a minor elemental (fire, water or earth) of your choice on the spot, whereas spell B allows you only to summon a major water elemental. Both spells are the same level. Which do you take? Once again it allows more choice and decision making = fun.
There is no choice when everything is available to you. Even with cool downs you just simply spam your best pattern.