I have the Royal backpack sluice and it works great for me. It catches very fine good with a good water flow. I can fit the Royal into my pack along with pan, classifier etc and hike into the back country with booth hands free. Hiking up the East Fork SGR is a two hand endeavor.
The problem with most folding sluices is they flex which is due to the pivot bolt holes being a bit large so the sluice can move enough to be folded. Most of them sag downward on the ends. Taping the joints is a good idea, but dealing with tape residue can be a problem.
I just saw that Keene has a new aluminum A52

model folding sluice. It folds into a larger package than the Jobe or Royal because the top funnel section is not removed. I believe Keene stopped production of the original plastic folding sluice because small sand grains got caught in the connection grooves making reassembly very difficult.
Al