in my mind this is something to flip to someone who can actually close it and operate it.. and I am surprised an owner got this far with out vetting the OP as a real buyer.. 

I'm not saying it isn't a good deal, I'm saying how many potential buyers can fund a deal like that?

I’d probably share in your concern in the single-family or small multi space, where the principals of the management company might also be the ones showing units, taking calls from prospects and making leasing decisions.In the large multi space, they probably wouldn’t steer residents to properties owned by the management company.

Just sell it with a quitclaim deed or do owner financing with your buyer.

For a decent quality note with a decent yield, there are a multitude of buyers at any point in time.  

Is this the best way to use funds to appeal to more buyers, or leave it as is and offer credit.

How do you qualify a buyer for a 4plex?

Should I at least get it under contract and see how the buyers react to it?

Yes, there are savvy and enlightened buyers who would buy it.

He probably will never be available to show it to your end buyer.