Well, the price sure is right. Were I not using United air miles, I guess I'd consider it.
Still, by the time one gets to Cozumel on that flight, it's after 8 pm, the day is lost. I'm happy with my 5:15 am flight that gets me to Coz at 2:15 pm. I'll be at my hotel, unpacked, and have dive gear ready for the next morning well before happy hour begins. Sunset, dinner, and the Delta passengers will be just checking in.
On the way back, I'll have to check out of my hotel around noon anyhow, so my 3:08 pm departure means I just taxi to the airport, get a drink at Margaritaville, and check in with time left over for the Grab N Go. With the Delta flight, I'd have to reverse the taxi to ferry to taxi routine and time it get to the airport around 5:30 for check in. That means I get a couple extra hours in Coz or PDC, but my flight arrives in LAX at 8:46 pm versus the Delta arrival at 10:50 pm, over 3 hours earlier. Also, I've already cleared customs/immigration in IAH, whereas the Delta passengers have to spend another indeterminate time going through that rigamarole. By the time one gets out of the terminal, it's after midnight, 3 a.m. Cozumel time. At that point, I have to take a shuttle (at least an hour) or drive home (45 min). No thank you!
I'm comparing apples to oranges since my flight is in June, not October. But there are other variables at work.