I'm also using 10.11.6 on a Mac Pro 2008. According to the product specifications, the current Paragon softwares support 10.11. I'm guessing each new version includes security fixes. I'd try to install the new version, indeed. If you have a Time Machine backup, this is even more a good idea: if you ever found the new version wouldn't work (which would surprise me), you can go back to just before you installed the new Paragon version (you have to backup just before you update, of course).

I'm actually trying to install some Paragon software on my Mac Pro. However, around one hour after the purchase, I haven't yet received my code (and nothing is listed under my paragon account). I'll reply as soon as I install the latest version.