I built a couple of these and they work great! After the first one you can build in no time! Most bang for the buck, especially when you get into the bigger tubs.
And remember you can use any tubs on a shelf ( as long as they are the same) as you are custom fitting each shelf height for those particular tubs. So you could mix and match different brands on different shelves.
Totally customized to what YOU want!! I totally agree with screwing the tubes in place too, absolutely necessary to keep from settling over time.