Yes, I used it once for a period of about 5 sessions with 9th, 10th, and 11th level characters. I caution you, only use it if you want casters to become vastly more powerful than they already are. The way it worked when we ran it was that casters would always open every combat with their highest level spells. The fighters in the group were disgruntled at being constantly outshined. It also makes items such as wands, scrolls, and staffs almost completely irrelevant. The only way I could figure out to make them useful was to simply allow them to be cast at will instead of having limited uses. That way, it simply enhances your spell repertoire.
A variant of this idea is that the recharge time is 24 hours for highest level spells, 12 hours for second highest level spells, 1 hour for third highest level spells, 10 minutes for fourth highest level spells, 1 minute for fifth highest level spells, and 1 round for all others. Hence an 11th level wizard could still only cast his disintegrate once per day, but he could get away with casting one cone of cold during the day and one at night, and his magic missile spell he could use every round if he wanted to (which is not unreasonable if you allow reserve feats if you think about it). Resource management is still critical at lower levels, but at least you don't eschew it completely. And limited-use items are still less desirable, but not as much.
Another good variant to reduce the multiple buff problem is to simply say that only one casting of a spell can only be in effect at any given time. So if you cast mage armor on yourself, but then later cast it on someone else while the other is still in effect, the spell fails (or the previous spell is dismissed).
