Atom feed not valid – do i update?

Feed Validator also informs me that my Atom feed “uses an obsolete namespace”:
<?xml version=”1.0″ encoding=”UTF-8″?><feed version=”0.3″

According to this help site, Word Press uses an older feed, not the Atom 1.0.: http://feedvalidator.org/docs/error/ObsoleteNamespace.html

Is it worth trying to update to 1.0, or is just having RSS feed valid enough?

Thanks,
John