You just can't go wrong with the BGT....just my experience, which is very limited....
I went out 2x w/ a "regular" sluice, worried whole time if it was setup correctly..... classified material, fed it slowly, then cleaned out.....quickly realized that my recovery was based entirely on how many buckets I culd run in a day, which was being limited by the "operation".
Now, with my homemade BGT, all I do is run material all day, clean out 1-3 times during the day. It takes longer to replace the sluice in the river than it does to clean it out ! Now starting to work on a prospecter size....
Can't reccommend them enough, even if a little $$$... increased processing = increased recovery... at least in my humble opinion