Ultimately, the decision is yours. But since you asked, here's what I/we'd do. We'd set up dates at vanilla locations to meet both the couple and the single male (not at the same time, of course). See what happens. You may find that the pics didn't do the couple justice, and the sparks just FLY. You may find that this hot SM isn't as great as his pics, or is a no-show. Either way, you won't know for sure until you meet them in person.
Many will tell you the dynamics of meeting a SM are simpler, since really only two of you need to "click", and your Dh just needs to feel comfortable with the guy. While I can see the logic in that, Mr. Sweet and I tend to prefer couples. But that's just us.
Good luck in your quest, and please keep us posted on what happens.
=)