In this recent thread, zybex and I discovered that the ~limit modifier doesn't work with List-Type fields "right" (or, at least, in the method that I think would be expected).
ISSUE:~limit works on the full string entered for any List-Type fields, rather than on the individual list entries. Therefore, if you want to make (for example) a Smartlist with one random track from EVERY [Artist] in your Library, you can't if you use [Artist] as a list-type field.
That's because it will consider
[Artist]=Taylor Swift;Bon Iver to be its own "discreet" artist. This means
that file will ALWAYS be included in the results (assuming you only have one of them) rather than including that track in the "possible targets" for both Taylor Swift AND Bon Iver.
The ~limit modifier is basically designed exactly for this kind of task, so that seems pretty broken.
SOLUTION:Can ~limit be changed so that it works properly with List Type fields? I can't imagine that people would want to actually limit it in the way it currently works with List-Type fields, but if you're concerned about that, another mode would be fine.
Alternatively, if anyone who knows the new fancy List-Type expression stuff and how it could combine with a Search modifier to work properly, please yell. I can't figure it out though because it makes my head hurt (and I suspect not). As I said, the current functionality is basically broken as documented in the wiki for its primary purpose though, so I think just fix it.