Hi,
The best and cheapest way to go is buying the Studio Ultimate Version 11 Upgrade (this includes Studio 11 Plus Upgrade). It may get confusing when you head down to the Upgrades page. There are two ways to get Studio 11 upgrade, 1.) is by acquiring the Studio Plus version 11 upgrade and 2.) through Studio Ultimate Version 11 Upgrade (this includes Studio 11 Plus Upgrade and the Ultimate disc).
Both can see your Studio 10 Quickstart as a previous full version and can use it to upgrade. But IMHO nothing beats a stand alone hard copy of the full version, no upgrade head aches to worry about, just a straight install will do the trick.
Marc P.