My impression is that Lojban is more of a research language than something people actually speak, but I'd be delighted to be wrong. It's beautifully elegant.
I agree that Lojban is a "research language", but that is certainly a good thing! Seen in relation to its size/popularity, quite a large amount of research in linguistics and computer science sprouted from it. I myself have comitted a master's thesis to the language [1] (on p. 29 I attempt to summarize where it was picked up in academia)
If you mean particular values of k then modern Lojban isn't compatible with non-infinite lookahead although pragmatically a high value of k may do the trick on real texts. As for SLL I'm no expert, sorry.
Did You Know... Lojban's regular enough that there's a yacc grammar for it? http://www.lojban.org/publications/formal-grammars/grammar.3...