The split infinitive sounds far, far worse than a preposition at the end of a sentence. But just consider the fact that the negative infinitive is formed with "not" before "to". "To be or to not be...???". An infinitive split with other adverbs doesn't sound so bad: "To boldly go where no man has gone before".
0 Faulkner on Tennyson (in "Light in August"):02br 02br 01i00It is like listening in a cathedral to an eunuch chanting in a02br 00 language which one does01b00n't even02b00 need 01b00to not02b00 understand. 02i0-