Paul -
Let me second, with enthusiasm, your suggestion to eagerly :-) consult Fowler. His treatment of the subject has been on my list of all-time favorites for decades.
I urge my fellow United Statesians to temporarily ;) put aside any reluctance to use a tome on *English* usage: the passages on Split Infinitives alone are worth the price of admission.
As I recall from distant memory, Fowler groups the reasonably literate universe into four types of reactors: those who a) Know what a split infinitive is, and don't care; b)Know and care; c) Don't know and don't care; and d) Don't know and care very much. It's that last group that is the nitpicking bane of competent writers. His treatment is rich with examples.
If the foregoing is an accurate remembrance, I put myself in a category between a) and b). It's not that I don't care, it's that although I can always recognize an infinitive, I will choose for myself whether and when to split it.
Patatty.