I have experienced amazing MMF threesomes! I've had a couple with my ex and a bi guy. And on one special occasion a girl friend of mine invited me to join her and her bf because he was curious to having another guy there. Safe to say he really enjoyed himself when I was the first guy to ever suck his cock ;) and mine was the first he ever sucked! He was great for a rookie!
I would definitely say yes! And I would suck him after ;)