Hi James,
I also have the 30 Royal and it's been great as a beginner. That said, the material does pack in behind every one of the larger riffles all the way down quite quickly and you probably think as I do that we're losing gold due to this (yes, mentioned in the last Gold Prospector Magazine). The only answer is a bigger sluice, but as Paul and William have mentioned it's going to take more water flow to run which means a couple months past spring you may start having difficulty attaining enough (I do with my 30 inch in the summer time!). If you go with a 54 inch, that wide-mouth might be the way to go, but make sure you can highbank with it as well, because I've learned that's the way to go (unless you get a dredge permit).
Happy hunting!
Clint