I personally think it would be nice to have an upgrade. uCoz lacks features that better forums (such as simple machines forum) have. Additionally, there is a bug with uCoz which keeps the "new posts" icon lit even if you have read all the new posts on the forum. You have to click on the "Mark all messages as read" link to make the "new posts" icon shut off (which is a tad annoying when there are people online, you can't tell if someone replied or not that easily.) The downsides to upgrading would be a lot of work moving everything to the new site and forums. Additionally, the current background on the SAMPS3RV forums and website might not be usuable on the new forums and website, and everybody would have to re-register.
Overall, there are some benefits the new website and forums might be able to offer, but it would require work and patience.