so I think its a great idea, if you can set it up to run faster or less maint.. and a few thoughts I had when reading your post and looking at the pics were...
make the basket so you can empty it without flipping the whole sluice. it looks attached to me but it just might be the pics.. But a quick basket flip (after a check for nuggets)
and you are cleaned out ready for another run of material..
second I think if you could set up a way to help wash the material in the basket with out a pump it would help you go smoother..
so if you did set it lower or added a ramp mid basket to force more water to wash the material.
drill some holes in the sides of your black catch basket so it doesn't block the flow of water going to the orange basket
I think the more flow you can get through the basket the faster it will solidify the material and go through the sluice better.
just a few thoughts but I think you are on to a good idea