At my workplace we have two email addresses, one from google mail (gmail for business) and one from MS Exchange.

I never had a problem with gmail for business regarding spam. I regularly receive mails from smaller businesses (some of them hosting their own mail server) and never had a complaint from anyone yet. Since i can also be contacted via phone i'd know.

On the other hand, MS Exchange constantly delivers obvious spam mails and (quite seldomly, but still) swallows legitimate mail.

Anectodal, i know. And disclaimer: the behavior depicted in the article is as bad as it gets, if everything is as described.