I had the CSW 6 and returned it, I wasn't impressed. The cone tweeter is obsolete.
I've never heard the L20T, but I'm not sure if it's worth getting a JBL bookshelf. I had older JBLS (L166) and they were fairly colored and a bit harsh. The main attraction of classic JBLs for me is the ass-kicking power, and you won't get that with a bookshelf. I'd be inclined to go for something more modern.