Well, it allows it to stand out from the other items on the workshop, so yeah. And if you look at the workshop right now, almost all of the promo images have a border.
i didnt test it in a private lobby. i did test it with the workshop importer tool - testgame. there are cheats allways activated update: ghost made it work anyhow.
Presentation in the workshop is everything these days(as well as popularity). I have my item, some screens but I just don't have the knack to put them into a presentable order to make it look nice. Can somebody point me towards a direction where I present my things in a professional manner rather than just dumping a whole…