I use the Combi Plan tank. I like it, some don't. Some things I have learned using it (which may violate instructions ). When setting the orange guides on top of the slots before loading, I use a rubber band to keep them from popping off during loading, then remove them before putting the ratchet clamp on top. When putting the lid on (I load mine in a dark bag), secure it pretty well, but after removing it from the dark bag, go around the edges, particularly the corners and press the lid to the tank edges as hard as you can. This will virtually eliminate any and leaks or dribbles during inversions.
Many complain about the fill and empty times, but I have found it really is not a problem, just take them into account. It speeds things up a bit if both "spigots" are on the same side and you fill and empty through the bottom one (instruction violation here, but it works and I have had no problems).