A few things to consider:
- QF sectors, i.e. will you be able to fly 4 sectors?
- Flying patterns within Europe: BA does not have "15/60 SC" band for medium length short haul economy/business class, if you know what I mean (only 40/80 TPs) which might make a difference to your qualification/requalification
- QF upgrades - as you probably know, you can't use BA Avios to upgrade QF sectors (including ODU)
- As mentioned already, QF lifetime status question, including LTS and LTG
- Australian credit cards earning QF points (you don't want to spread the points/miles etc. too thin everywhere)
- Most JQ sectors can only be credited to QF and you cannot use the lounge when flying on QF on the basis of a non-QF OW status
- Redeeming on EK is not an option with BAEC
- Status bonus not mutually available between BA and QF (unless on codeshare)
- There is no equivalent of Any Seat Award with BAEC (at least not yet)
- Money off with Avios option on BA flights is available with BAEC Avios but not with QF points
- Last but rather importantly, BAEC won't be available to you once you move back to Australia
Do think about your options, your current lifetime status credits, and flying patterns carefully before shifting programmes.
I'm an "ex-QF Platinum"- I did not move over to BAEC despite living in Europe until I had the Lifetime Gold with QF.