If you like it now, buy it. LFS will only get better with updates, not worse. There is no point waiting for the patch because if you like it now you'll like it after the update too. It's not a complete makeover, just improvements on known issues.
As the community grows (with the introduction of the BMW Sauber F1 and other stuff) there will be more people to race with on a whole lot more content than the demo. The demo isn't really representative of the licensed side which has (pro) leagues, organised races, quality competition and very seldom does one come across drivers who intentionally wreck others.
WHY HAVEN'T YOU GOT THE LICENSE ALREADY??? GOGOGOGOOGO!!