Allrighty then,
Speaking as one who has been the F in a couple of MFM's it can be quite an erotic experience.
It is also one that must be well planned out in advance so all parties involved are on the same page. You wouldn't want a large penis in the same room with a gent with size issues, you want to be clear on who will be touching whom, whether or not sword crossing is acceptable. ( always occurs in porn, 2 penises in one orifice)
And of course the rate. I personally do not "supply" any participants for this activity. I do however know of a few men who have expressed an interest and will let them know when something like this is in the offering.
The rate does reflect the fact that neither man has me all to himself, but an MFM is truly twice the work for the same amount of time. LOL
Because I do enjoy what I call my kind of duo,
I do offer a reduced rate for the gentlemen involved.
Some folks are into it, others not so much. Same as most other activities.