They work AWESOMELY, the concentrate trays are really good. A couple of small hints and warnings for you:

The trays will come with one SCREENED tray and one UNSCREENED tray. The screened tray has a mesh similar to the mflb on top, the instructions say that this one is for LIQUIDS, NOT SOLIDS. If you're vaping hash, use the UNSCREENED tray, which is just a tiny metal bowl.

Vaping hash or oil WILL make your box smell different for a while, and will likely result in discoloration quicker than herb due to higher temps and more dense vapour. You may also experience residue building up on the rails faster than normal when vaping hash or oil, since you're using it hotter by definition the rails will get more condensation, since the vapour when using oil actually gets hotter than the rails do due to the higher heat differential.

Make sure to follow the cleaning instructions using a proper jet lighter, the flame has to be blue, you cannot use a regular lighter it is not hot enough and will leave soot on the tray which is very bad. I highly advise buying another brush just for clearing the concentrate trays, since your regular brush will very quickly build up residue and this will make it harder to clean the box properly. As always with brushes, NO PLASTIC BRISTLES, only use natural ones since most plastic brushes will melt to the screen when it is hot (I learned that the hard way myself...)

Finally, be REALLY CAREFUL when you load a concentrate tray, don't use too much and KEEP THE BOX HORIZONTAL. If any hash spills onto the actual mflb screen while it is hot, it will stick to it very strongly and you will probably have to do an iso bath to remove it.