Was just wondering people's thoughts on whether there is any added value in listing/selling sets in themed group.

What do I mean by this? Just say you have all the City Mining sets, ie 4200-4204+poly. Is it better to sell individually or to sell as a complete set? Anyone had any experience with this type of thing?

You might be limiting your market by doing this, some people might not be looking for all the sets in a theme, just one or two of them.

I am of the same mind. I try and collect a whole series of a set and would prefer to sell as 1 lot, but you may get more separately. Wait till all EOL and maybe better that way

What about selling used sets, would you sell all as a set or individually?

Again you get more generally on single sets, but if you have a rare or expensive set, then grouping them together can push it even higher.  Depends on the sets you are listing.