I need a new shopvac for work, we use them to suck resin out of large commercial water softeners. The resin is very small plastic beads (about the size of a ball on a ballpoint pen) When we do this the resin is usually wet or damp and so its very heavy. We have a 20gal shopvac brand vac that we have had for years but its time to replace it. I have heard that Ridgid vacs are good, not sure if they are or not. I think for this type of use the amount of vacuum pressure that is created is more important than CFM. Shopvac has specs for their vacs for cfm and inches of sealed pressure ( I'm assuming inches of water column) Rigid only has cfm listed that I could find. Any thoughts on which brand is better or other brands?