That rack looks great. I've experimented with all different group sizes in all different tubs sizes, and I've found that my best, most consistent production comes from 1.2 and 1.3 groups. I know a lot of people do 1.4, but over and over my other groups have out produced these groups. Have you had any issues with them chewing out of the tubs? Mine have eventually chewed out of every tub I've bought.. But if those are really heavy duty then I'll give them a try.