XML doesn't require a ">" in text data to be encoded, but any character in text data can be encoded.

Or maybe you're playing with the idea that it's not text data. If so, neither would work as both encode the "<" as if it was text data.

Personally, I consider the full-encoded RSS to be "more valid".

So you always escape "!", "?", "[", "]" and "-"? They are no more and no less special than ">". Each is a special character in the right context in XML, and each is perfectly ordinary in text data and attribute values.