I've recently been on a hunt for some way to further refine the black sand concentrates I bring home from sluicing or panning or other methods. A half bucket of heavy black sand super cons and gold mixed in takes forever to pan out. So. Here's what I've tried so far.
(Disclaimer. These things might work great for many. These are just my experiences.)
California Bucket Sluice Concentrator. 
(lightweight thin plastic form). Inexpensive. About $30 plus shipping.
Hose is barely long enough and keeps popping out when flow is reduced no matter how tight I wiggle it down.
Black sand cons quickly filled up the rib shapes along with the gold then everything just swept through. Increased flow cleaned out the ribs better but also took out gold. Adjusted flow and slope different ways but still limited results. I finished panned the tailings. Same as what was in the gizmo. Didn't work well for me. Maybe it's for blonds and larger bits. Or, maybe it's to reduce material down to black sand cons and that's about it.
Micro Clean Up Sluice Jr.
Very innovative. Everything fits in a bucket. About $130 plus shipping.
Comes with extra parts which is nice. Square mesh metal over rubber rib mat. Plastic sluice tray.
Metal cross clips and plastic tubing over the metal mesh quickly plugs up with black sand. I tried taking the clips off and also the mesh. It worked better. Kinda like a miller table with rubber ribs. Works very well with very small gold to fine mesh. But flour gold will wash out and if flow or slope is reduced then it will plug up quickly with black sand.
Needs to be cleaned out often because it does not work well as the ribs fill up. If flow or slope is increased then that will increase losses. Larger gold that doesn't fit in the ribs will wash out. I finished pan the tailings and got some fine gold but not too much. UPDATE: This is a handy portable gizmo for site sampling. Takes less than 5 gallons of water. Portable. Everything fits in the bucket. I'm going to try testing it with Vortex matting and some Gold Hogg matting to see if it can do what it is supposed to do.
Black Magic Miller Table 
About $105. This works for most gold but not flour gold. The slope and rate of flow adjusted for flour gold does not wash away fine black sand. For larger gold it works fine and as advertised but painfully slow. Like the Blue Bowl, the flow has to be adjusted constantly according to what is happening on the table to get best results. Super fine black sand cons give it a hard time if there's flour gold mixed in. Reduced flow and slope works some for that but did I say it was slow? Might be the answer for those that do not enjoy finish panning. I'm not sure how other "miller tables" with different finishes work so this is not a comparison. Also, some shapes of gold like thin flakes will catch the current and wash out.
Blue Bowl 
About $130. This works well for most gold but not flour gold or light thin flakey gold because the current that is enough to wash fine black sand away will also lift that type of gold as well as flour and micro gold. They wash out and the micro black sand stays. Larger gold bits are okay. The Blue Bowl has a severe learning curve as far as techniques to adjust the rate of flow as well as how to manipulate the currents. It also has to be watched very closely and adjusted according to what is happening. It is not a walk away and forget machine. In the hands of an expert with a lot of patience this is a great machine. But, it is somewhat slow.
Gold Rush Nugget Bucket (classify and concentrator)
About $110. One bucket of material run through. Heavy Arizona black sands, clay, and river gravel. Bottom catch bowl fills up quickly with heavies and then everything coming down flows out through the sides. The catch bowl was surrounded by a mound of black sand while heavy clays gunked up the inside of the bowl where the "gold ring" was supposed to show up, or at least heavier gold. Nope. Cheaper to preclassify with regular pan classifiers and run the result through a garett supersluice pan. The cons will be cleaner and definitely way way less loss of fine gold. I contacted the sellers and their customer service was outstanding. They reminded me to fill the catch bowl with pebbles to prevent cons blowout. I had indeed tried all kinds of combinations but it still got overwhelmed with heavy black sands and clay, typical to prospecting in the Bradshaw Mountains. The vendors gave me a full refund which was great. They will be coming out with a model with a deeper bowl soon. Hopefully it will solve the blowout problem. Will keep you posted.
And, finally, after spending all that time and $ messing with gizmos and gadgets. . . . 
Finish Panning the Regular Way
ProLine 14 " green wide bottom gold pan and blue Falcon finish pan and a small white dish tub from Walmart. (and jet dry)
Less than $25. This works everywhere, doesn't need a pump or batteries, just good eyes and patience. With a safety pan, losses are near zero.
Interested in what others are doing to streamline the process.
Thanks, AlohaJim