MM4,
I am unsure whether I have understood your point fully, but the announcement of the scheme design for FAFPS will have no bearing on current or future PAS pay scales or any other pay scales. FAFPS will just be interested in how much pensionable pay you earn each year and do not expect SP(F) to become pensionable from 1 Apr 15. Its austerity, innit.
Given that the value of your FAFPS will be based solely upon your annual pensionable earnings from the date of its introduction, once we have an accrual rate you could work out the value of your future pension using current pay scales, which would tell you its comparative value at today's rates. This is no different to AFPS 75 or 05, whereby the Pension Calculator uses current pay rates to calculate your projected pension based on your projected length of service and rank on your forecast exit date. As you know, what the calculator tells you that you will get is not what you would receive as it is based on current pension rates and does not forecast future pay increases whose benefits would have a compounding effect. FAFPS will admittedly be more difficult to predict because you will not be able to forecast what future pay increases will be, as now; the date of future promotions; the annual revaluations rates for your annual pension contributions etc, all of which will also have a compounding effect. The FAFPS Team have initiated work to develop a FAFPS Pension Calculator that may be available middle of next year.
Given this, those assessing whether to accept PAS or not should, IMHO, use current pay scales to compare basic and PAS incremental pay scales and apply a set accrual rate (say 1/70ths from AFPS 05) and consider which they would be better off on under career average. Once the FAFPS accrual rate has been announced, which may not be too long, just update the accrual rate to give you a more accurate idea of the delta, mindful that many public sector schemes are settling at around 1/60ths, so ours should be higher.
With regards to future changes to pay policy, don't hold your breath, I think concrete proposals may some time off yet.
Here endeth the lesson.