The watch is indeed wonderful, but it don't think it's particularly rare; I've seen it in AD cases more than once since I bought mine two years ago. The reference is 192.029. www.alange-soehne.com
I can't really answer because the two are so different: Swiss vs. German, totally different complications, totally different metals. Also, I've never seen a 5110 in the metal. That said, I can report that I've thought occasionally about trading this Lange...
The 5110 case lines are very organic and graceful and my feeling is that the Patek has a more interesting movement appearance because of the microrotor and the overall "romantic" movement design. On the other hand a moonphase itself is truly a romantic co...