Have done an FMF but I ended up running out of steam way to soon. MFMs are a lot better, and I have had many of those. Actually, my GF loves MFMMs as she likes one guy sucking each nipple and the third sucking her clit. She needs a lot foreplay and sucking of her clit before she cums. Having two other guys there means we can rotate when the guy who is sucking her clit has his neck get too tired.
Actually, having two guys with us in an MFMM works out great because she can wear out all three of us before she is satisfied.
Here she is trying to get me and another guy hard with her hands while she is riding another guy's cock. He was the first one in her after we worked together and made her cum. Because he was sucking her clit when she came, she had him do her first. The guy on her right is next, and then me. Guests usually go first.