There is a published feat (Hide Spell, Relics and Rituals) which says, in essence, that spell that can not be seen or hear does not have a reflex save, baring uncanny dodge. Some people call the feat crap, and it isn't core D&D. At least it is one publisher's opinion.
As for QttE, it seems in most respects like a specialized/advanced version of feinting in combat. Think of football. They try to grapple you, you try to run around them. In a lot of cases, players "feint" others, run through "threatend" areas, and are not subject to "AoOs". Stupid example maybe, but it does show feinting in a combat like situation. QttE would be this sort of manuver but using raw speed rather than guile.
On the other hand, invisiblity/feinting/QttE is already powerful. Preventing all AoOs seems to make it even more powerful. If you like this as a 2nd level spell, maybe you shouldn't expand what you know they can do into what you think should do, just for the sake of balance.
Personally, I like the "No AoOs if you don't know exactly where they are and what they are doing." A fighter, in my view, only really swings when they want to or when there is a convient opening, unless they willfully decide to swing wildly in cases of invisible oppents.
