Well drat. It was a perfect replacement (thankfully I hadn't started moving files over, was waiting to get Cloudflare setup), until I noticed in their ToS that they don't allow:
"(A) any information that is unlawful, harmful, threatening, abusive, harassing, tortuous, defamatory, vulgar, obscene, libelous or racially or ethnically objectionable, or promotes such activity"
I'm waiting for a reply from them to see what exactly is meant by vulgar and/or obscene, since we do have what could be considered adult illustrations. This does make me wonder now if there are other decent s3 replacements?