Thanks everyone for your feedback. I was under the impression that it was possible to commute for these CX positions - having to reside in HKG will make it even more difficult for me. Its a bit worrying that it could take so long for a promotion but that doesn't really bother me too much other than should I choose to change employers after a couple of years FO experience I'll be at the bottom of the seniority list of the new company and pushing 50 so that's not ideal.
The only other question that is raised from all the comments above is, based on the feedback, it seems that career progression in CX is quicker by racking up couple of years regional/GA time then applying DEFO rather than joining as a greenhorn SO. Doesn't really seem fair to SO's.