Is it actually limited to 8GB, or is that just what Lenovo says/is willing to support?

My x220 limited to 8GB in ever bit of published Lenovo literature, but I bought 16GB of RAM at the same spec as the 8GB I have running now and everything works fine.

I upgraded my Dell Latitude E6520 to 16Go while it is supposed to be limited to 8. Don't be fool by the manufacturer specifications.