I don't know if it really counts, but I used RNGLR for the programming language I've been working on, and have been planning on replacing it with a GLL version in a bit. RNGLR was fairly complicated, and I did find the paper a bit hard to read, which might have limited its spread somewhat. When messing with the syntax for my language, it was nice to only have to worry about if my grammar was ambiguous rather than weather it would fit into LL, LR or LALR, and made it easy to change syntax very quickly without changing any actual code.