I've never tried it or considered it, and it doesn't seem to appeal to me, generally speaking. But on another level, under perfect circumstances, it sounds kind of good.
Of course there are never perfect circumstances are there! Darn it! So I don't believe it would ever work out for me. And if I were in love with a man, I know I wouldn't even want to do it. But I think a large percentage of men would like to try it at some point; society and wives in general don't support it though, so they never do it.
But no, I don't consider it cheating at all, if it's something the couple agree to do. Unfortunately, it would seem like feelings would always be a problem, for at least one or more of the participants, at some point.
Like lines of emotional intimacy being crossed.