I've decided to take the existing flights w/out changing or upgrading, primarily because:

1. Upcoming weddings (my own and a friends) back in the UK mean at least two SYD-UK returns next year, for which 42k AVIOS will no doubt be useful;

2. Changing it will just open more questions back at base than it is worth;

3. I haven't flown PE for a couple of years, and could probably do with a reminder of why CW/J is worth the effort.