Thanks for the replies guys, very helpful in making up my mind.

VN option is the logical one. Guess I've been flying too much BA WT+ to remember than PE really is better than Y. Won't get any time in SGN, but will get more time in PNH with that option. New to skyteam, so interested to see what it has to offer. Status matched due to a one off promoting and for exactly these kind of reasons. Only reservation would be about loosing elite qualifying miles which I may or may not need come the end of 2016. Having said that, qatar was pretty meh last time I flew them in Y, so not jumping for joy at that opportunity. Thanks ahain