Well, let's not forget the important contribution of jgreen, who sits around all day listening to FLACs (Caution: Just kidding).
In fact scthom single-handedly wrangled MC 11 FLAC support, writing the code, studying obscure audio theory, and fending off the nay-sayers (a surprisingly important job around here). The end result after all his hard work is that FLAC support in MC11 is complete and seamless, as well as thoroughly-discussed. As Alex B said, there is no need to stop by the third-party plugin forum, unless you just want to witness hair-raising drama.
Alex also provided some other links, which I have a feeling include the following points:
1. MC 10 libraries are upwardly compatible with MC 11, but not the reverse. Make certain that you back up your library, and then back it up to a second location unrelated to MC, just to be sure. Any additions you make to the library in MC11 will need to be re-done if you go back to MC 10 and use your backup library.
2. The latest stable version is 11.0.316. There are alpha versions of 11.1, but there has yet to be a pain-free version. Additionally, 11.1 has compatibility issues with 11.0.x as well as 10.
3. 11.0.316 is a great version, I use its near-twin, 11.0.314, all day long, blasting FLACs to beat the band.