My wife and I have had great fun with this. Mainly with Eros type gals that are not cheap. After doing it 5 or 6 times is got a bit boring to be honest. I always have to be a bit more reserved and make sure wife isn’t being left out, when I just want to go wild with the provider.
Oddly I enjoy our mfm stuff more than the mff these days, wife just goes insane getting DP’d, it’s a blast.