How long have you and hubby been with the other couple? I ask because while I have not tried polyfi, the people who have sometimes note that it evolved for them as natural growth in the relationships rather than as a precondition. I'm reading into your brief message here but if your quad is new, polyfi may be premature.
And is this what you want? Your hubby? It's ok if it's not. There's lots inbetween monogamy and polyfi that may work for the 4 of you.
P.S. Love the username! Made me giggle.