Love, love, love Mercantile. It might take a few days for the editor to finalize the report, but the editors ask reasonable follow-up questions. Not like the MSCs that make me feel like they're only asking questions so they can put in their report that they had to follow-up, and therefore have to deduct some of my payment.
Mercantile always pays the full reimbursement and fee. I've been with them for years. Love them!!