All the rumours that I have heard (which have originated Manning DOs) have the new RRP(Fg) package improving for all when looked at over the course of a career, so you might be pleasantly surprised. Ultimately the changes are being made to retain people, and they aren't going to do that successfully by introducing a package that sees people worse off overall.
If you are still in phase 2 training then I would probably prepare yourself for the likelihood that you won't receive retention pay during your initial 6 year RoS when you are contractually obliged to stay in the RAF. But after that I reckon there is a good chance that you will be better off than if you had stayed on the old system and worked your way up to middle rate flying pay.
Of course, until Manning release some facts, this is just rumour, but Manning DOs have been discussing it with front line personnel, so there should be at least some truth behind them.