If you have already flown LX F a number of times and familiar with it, OZ F is certainly not an airline that would make you regret giving them a try. Various elements of the OZ F experience might not necessarily be better than LX F (the seat, for one) but, as someone who enjoys trying out new airlines and products, I would not consider it a particular downgrade to fly OZ F over LX F.

Although I have no personal experience of bad service on either carrier in F, people do say that LX F can be very occasionally variable. OZ, for sure, has exceptional service - however, I'm not sure how any problems with English proficiency plays out with non-Korean passengers.

I would say that food is much more geared towards the European palate on LX, and if you are catching a night flight ex-ZRH, the pre-flight dining is very good as well. OZ F on my recent NRT-ICN flight had spectacular catering for a 1h30m flight and I'm sure longhauls won't be drastically different.

Here is a very good trip report by KevinCM who flew the exact same route a year or so ago:
http://boardingarea.com/blogs/ghetto...iana-and-thai/
(But bear in mind that OZ F seat on the 777 is different to the 747, and should be considered roughly equal in quality to the LX F seat.)