I think it's possible for them to run out of your first choice, for sure. I've flown LX J many times, and I've never had that happen to me either as a non-status passenger or as an FTL or SEN. LAX-ZRH is also a night flight, so maybe some will opt out, making it less likely that you won't get your first choice. The flight time, however, is conducive to a meal and getting 8 hours of sleep (I find that from BOS/NYC, they're pretty mutually exclusive).
I haven't flown LX J in over two and a half years, so can't comment on whether not getting your first choice happens now more than then.