NC_Seniors - If you're just mainly looking for a MFM experience, why not just enlist the male half of one of the couples that you already know that would be willing to help you with that? Are you looking for more of an on-going poly sort of thing?
For us personally, we don't play with cheaters if we can help it. It's more of a karma thing than a judgement or "risk of gettitng caught" thing. We've made one exception in our 10 years in the LS with a woman we got to know over a span of 6+ years first.
We do lots of MFM's or MFM+'s at LS parties, and there's always a chance we've played with a cheater. We just don't play with them in the future if we find out. We otherwise can't relate directly to the OP's question because it is extremely rare that we'd engage with new SMs outside of a LS party. It interests more as time goes on but, for now, generally it's guys reaching out to us rather than us actively looking and interviewing SMs online.
Just curious, but once you do find an acceptable guy, what would need to happen for you to actually pull the trigger on it? Sounds like a lot of work so far for a "maybe we'll try this" kind of thing.