I have created a 'Gallery Forum' and put a large Gallery icon high up on the forum to attract attention. It works a treat and visitors are clicking on it far more than when relying on the forum link itself. As this 'Gallery Forum' is likely to get a great many pics on a thread I have limited the display of small thumbs above the topic title to just 8. What would be a good addition is some text stating something like 'Recent Pictures Added' whenever the thread thumb limit has been reached, displayed above the 8 thumbs. As it is if more than 8 pictures are added to a thread it appears that only 8 pictures are there but, of course, there could be a lot more. Also whenever a user clicks directly on the thumb he is taken to a post where that picture resides but this can be confusing if a few posts have been made containing pics in a thread, so some text explaining about the thumbs above the thumbs themselves should help reduce this.

"Thumbs above the topic title" should just change to the most recent thumbs uploaded, showing them. It works on many forums and attracts attention much more than if we would put any text (to that, some extra text above or below the topic's title would make it even more confusing).

What about this, with the above thumb text only kicking in once the set limit of thumbs has been reached?

In theory, it could be possible. But the main problem about it, is that the current version of the add-on doesn't store the total number of uploaded files as the static value. So either the script should be improved for that (and that's lots of changes, because it's actually planned for another purpose and the method of implementation); either it's possible to turn on the current methods, but then, for each topic, the script will count the number of files in a certain folder - not sure if it could be quick.