The point to remember about any process is to classify down to as near the size your gold is;
that is if your gold is mostly smaller than ( for an example only ) 20 mesh then screen every
thing with that size first, check everything larger for oversize before discarding it as a stray
clay or mud covered nugget or specimen may have got by your first inspection.
As with any process, there is a learning curve to any you decide on; always rerun or pan check
what you process to see if your equipment is doing all it can and should do, leave nothing to chance.
I own and use two spiral wheels and have no complaints about them. A blue bowl will recover
finer size gold ( at the expense of speed and through put ). The Blue Bowl has no moving parts
it's recovering action is by spinning water around it's center post where the wheel has riffles that
trap the heavy's and carry them to the center and deposit them into a hole where they fall into
a recovery cup. The newer equipment known as a gold cube is a step up at LOTS more expense, but
works very fast and recovers down to -200 mesh when set up right. As with any thing there is no free
ride and you can't have everything at one time. Buy what you can afford and learn how to use it.