In our experience, LCBR is great about comping gear if your bags arrive the next morning. We haven't missed any dives and our bags are there when we return from the first morning two-tank. We've had it happen a couple of times over the years, so it is a possibility. Definitely a good idea to put your DC and prescription mask (if you have one; we're old so we do ) in your carry-on. We usually go in the summer so we rarely wear wetsuits, but we do put a couple of skins in our carry-ons as well.
True, during our last trip to LCBR a suitcase with most of our clothes was delayed by a day but I had swimsuits, undies and other essentials - like contact lenses, medications, and C-cards - in my purse, and the resort staff kindly laundered our outer clothing for free so we were fine.
Another couple had the bag with their gear delayed and the dive shop loaned them gear for the first day of diving. Everything showed up the next day. I don't think it happens often but it does happen occasionally.