Our proofreader, a native speaker of American English, just won't let me use this word. Every single time I try to sneak it onto one of our sites, she replaces it with three times. Now, I do realize that thrice is quirky, but how quirky is it really? Is it awfully archaic? Is there a chance that native speakers won't understand it at all?
I know I could just search a corpus or five, but I don't feel like looking at cold stats (or the Wiktionary usage notes, for that matter). Instead, I am asking members of this community for their very personal, highly subjective, extremely biased opinions.