This grommet version is gorgeous and adds nice water proofing protection. For those concerned about moisture, this is the best design I've seen here! Looks like it adds about $10 to $15 more per controller to buy the more expensive 3 wire ends, and a lot of grommets. I am comparing to the SPT2 wire and ends, or to the $.50 Dollar store extension cords. Both of those ideas cost about the same.
I am going to experiment with sizing FOUR grommets to each hold 4 SPT2 wires tight. This keeps the cost lower since I have to a lot to build. Six of mine will have Dollar store ends, and the majority will be SPT2. I hope to get the 4 wires tight in each of four grommets, and might just add a dab of silicone to each one. If it gets too much, I might cave in and just tie-wrap groups of 4 wires on the holes already provided.
Since 2009 I have never seen water get into a CG type case, as long as it was mounted vertical. I also try to make sure the top of the CG cases are always against a board or a mounting surface, to be sure the water cannot drive horizontal into the top edge of the case. I make a yard stands that hold 4 CG1500 cases (two each side back to back). I prime and paint the frames good. But to make them last longer I usually put a large black garbage bag over the top. They hide better in the dark that way too. But I did get lazy last Christmas :-)