White Noise
The decision to opt out of the AFPS, be it AFPS75 or AFPS05, is open to you only during the first 6 months of your Service. That is, you can only opt out at or within 6 months of first joining. Should you do this, the scheme rules allow you one opportunity to apply to reverse that decision at a later date. You cannot opt out later than 6 months into your service, and the transfer from AFPS 75 to AFPS05 is not an opt in/out decision in the same sense. If you leave the service now, from within AFPS75, and were to rejoin at a later date after the transfer date, you would automatically re-enter under AFPS05 only, unless you opted out of the AFPS altogether in favour of personal arrangements.
That's my understanding.
Regards
Ginseng