woodburner,
I've used the "box over the top" method as well. It's crude, but it works for certain applications. It's useful enough that I made it a bit more permenant by hooking a threaded flexible tube to the top hole and piping it into another chamber. This method has it's advantages, mainly that you can create cold smoke for a long duration. If you're prepared to keep refilling the woodbox, you can create a very light smoke this way indefinitely. I make a gravlox with this method for example, and I'm happy with the results. It's not all that efficient in terms of killowatt hours consumed, but it does work.
However, when smoking cheese I find that I need a heavier smoke then the boxtop method can produce. A very light smoke, even for a long duration, never seems to create the deeper color and flavor that people look for in a smoked cheese. That's why I use the method described earlier. It makes for a heavier smoke which seems to be more effective with cheese products.
As an example, here's some cheese smoked in a cookshack using the earlier method. It has a deep color, as well as a fuller smoke flavor.
Pecorino RomanoRegards,
Joseph