I don't have first hand experience of Shoretrips, but I've been on the trimaran and it's a beautiful boat, you should have a great time!
Those looking for snorkeling tours may want to consider Paradise Beach's new tour too, it goes straight from their beach, so you can enjoy relaxing and get some good reef snorkeling in too. See
www.paradise-beach-cozumel.net for more info...
Ian