Hey Mr. Mike Drew:
Don't hesitate. Get the machine. And figure out how you are going to pack it later.
Personally, I do not own the machine. Yet it is on my list for "next". Right now, I use the Hog Pan. The waters I now work are deep & fast & the Hog Pan easily out performs any river sluice in my case. Besides, I work alone & turning my back on a river sluice so to fill buckets is unsettling.
I've studied Doc's river sluice & mats. Cadillac equipment. As for classifying, of course you don't shovel 5 or 10 pound cobbles into your bucket / sluice. Rinse em off in the bucket then drop em. A mat like the Talon (Doc's favorite, I heard) allows for the larger cobbles to roll over without touching where the pretties are stored. Yet the mats are rubber (way strong & stiff rubber @ that -I've the multi-sluice) & will bend / distort if the weight is too great. So really, anything baseball size & over, rinse then toss. And the more of the larger then the slower I'd feed the sluice. Let it breath, so to speak.
Again, personally, I do not own the machine. Yet it is to be my next investment. I've grown weary of (Garrett) pan'n my buckets of Hog Pan cons. Seeing how summer is tomorrow, I now envision myself slamming out buckets via my Hog Pan into way way way fewer buckets of cons. Then @ the near end of the day, with as many buckets of cons as is possible, opening some river-cooled cold ones while sitting beside & spoon-feeding (for maximum catching of all gold & gems & enjoying the end of the day -no lifting) my newly purchased Gold Hog River Sluice that Doc (thank you) has changed the industry with. How brilliant this man is.