We upgraded all of our forums to 4.1.5. That includes VBForums. The other forums you listed are not ours, so I can't speak regarding them.
There are a number of tweaks I've pointed out to the developers that need to be fixed on this site. I've a list showing some are fixed and many are still in process today. You should feel free to point out specific items in this thread or the feedback forum.
As to the width - the forum should work at a smaller resolution than 1500. It works best at 1280 or higher for the width, but that covers nearly everyone coming the forum at this time. (( We know mobile devices aren't running at 1280 (yet), so we will be looking into that ))
again - any other issues you see, let us know. Even if I've already pointed them out to the developers, it doesn't hurt to have you guys mention them too.