The misnamed "split infinitive" construction, where a modifier is placed immediately before the verb of an infinitival complement, has never been ungrammatical at any stage in the history of English, and no confident writer of English prose has any problems with it at all. (As the grammarian George O. Curme pointed out in 1930, it's actually the minor writers and nervous nellies, the easily intimidated, who seem to worry about it.)
This is not even a descriptivist vs. prescriptivist issue, because most reputable guidebooks about language agree with Pullum's reasonable position on the matter. The prejudice against this construction only emerged in the mid 19th century and was never a grammatical rule before that.
The problem is not whether to split an infinitive or not, in my opinion, but whether to place too much emphasis on this kind of shibboleth, as though good writing were mostly a matter of observing arbitrary zombie rules. It could be said that certain concepts like the split infinitive actually serve the purpose of the shibboleth better than real grammar rules do, since they are harder to observe consistently (to consistently observe).
In the biblical story from which the word "shibboleth" derives, people were killed based on their inability to pronounce a certain phoneme. The purpose of a linguistic shibboleth is to exclude people who don't observe certain niceties.
If you disagree with me, go argue with Geof Pullum. I have no interest in debating this point with anyone.
