Smooth as silk. The single-sided FMM form I printed was accepted with no issue in CUN. The immigration agent just tore it in half, stamped both halves, gave me the one side and said don't lose it. The 2nd page (with the instructions) he tossed in the trash. We were not given a customs form on the plane, and no one wanted to see one. I just walked through the "nothing to declare area" without issue.So let us know how it goes.
(The longest/only delay was waiting for the bag at the carousel - almost 25min while a million bags from a DFW flight came out.)
I got pesos from a Santander ATM before exiting to the street (declined the lousy exchange rate they offered), and used WhatsApp to text Jose, Chief's guy, who has you wait at the Margaritaville by Terminal 3. Sent him a selfie to aid identification. Jose sent Sergio to drive us. We pre-arranged a roundtrip fare of $95, (more than the ~$80 Chief mentioned, but I didn't feel the need to keep haggling.) I gave Sergio $50+tip, and will give $45 after the return next week.
It took 45 min from CUN to the street at the ferry, not counting 5 min stop at 7-11 for a can of Modelo Negro. The bag drag to the ferry wasn't as long as I recalled from last time - maybe 5-7 min?
Winjet and Ultramar are both running every day, alternating departures on the hour. We made the 5pm ferry on Winjet; the 6pm would have been Ultramar.
Bottom line: my flight arrived CUN ca. 2:45, and we were on the ferry by ca. 4:45. The bag drag let me get a non-stop to CUN from PHL, which was well worth it, IMO.