I will have to get back to you about the effects of silicone on leather (can't find good info by Googling): it may be more superstition than science, but I'm still not convinced enough of the benefits to risk the consequences. Either way, I don't want the quick shine nor the slip on my saddles, so it's moot to me.
"Neet" or "neat" is an olde English term for a bovine, so neetsfoot oil is oil derived from the hoof of a beef, or a cow if you prefer. (at least that's what I've read)