i guess having the CASA class 1 doesn't mean anything then?
The only bonus I can think of is you could be exempted from doing the second check-up for the CASA Class 2 after you are accepted as a cadet. I'm not sure about that though, but it seems quite logical a guess. I have a current CASA Class 1 medical, and I had to do the entire initial medical checkup again. I even had to get my eyes checked, but reading about what others have gone through makes my case seem like a non-event.
Good luck to everyone still waiting for a flight grading invitation. Hang on in there, they should be quite keen to take you on, if not they would not have spent money flying you into HKG for Stage 2 and 3.