I have one, use it exclusively for panning hazelnuts--although it can be used for many other items. Maximum weight of "raw" (uncovered) hazels is around 1 kg, with the shell being around 6 mm thick. Really, it all depends on how thick you want the chocolate shell to be, there's only so much space in the bowl for the nuts to "grow", thicker shell = smaller amount of "raw" nuts to begin with.
You need a cool room (ambient temp of 13 celcius or lower) or an air-conditioner for panning chocolate items, although some have "cheated" by throwing in a hunk of dry ice, or stuffing the whole contraption in a fridge.
The hallway in my commercial bldg is just the right temperature in the winter months, I set the whole thing--K. Aid and device--on a trolley and wheel it into the hallway. In the summer months I do it in my kitchen, I have a cheapo air conditioner that I added a 4" dryer hose to, and can direct a flow of cold air into the bowl.
If you add to much chocolate into the bowl, the surface on your items will be "wrinkly". I like to fill a large squeeze bottle with couvertute and squeeze just enough choc, into the bowl to gt the items wet, then tumble around for a minute or two, direct some cold air in, tumble a bit more, add more choc., etc. etc. etc.
Glazing is lost on me. I tried with gum arabic glazes, but didn't have much success. High glosses with gum arabic is dependant on the cocoa butter content of the chocolate. I hate cheap chocolate so the glazes don't work well with my regular 70% couverture, There are commercial glazes, but I don't know of any sources to get small quantities, and they contain many "funny" ingredients. I finish off my hazels with cocoa powder.
Cleaning the bowl can be easy or hard, all depending on how you look at things. I run the heat gun around the outside of the bowl for a minute or two--or toss it in the oven, and then remove all the chocolate and cocoa powder residue with a plastic scraper. I re-use this on my next batch for the first coating--the cocoa pwdr helps a bit to make the first coat stick. Or you could try to wash the whole thing in the sink and wash about a kilo of choc. down the drain and plug up the pipes.