Similar position to Backwards PLT - Flt Lt PAS, early 40's, AFPS 75. From playing with the pensions calculator, for those in a similar position to me there doesn't appear to be a financial downside to accepting the offer of service until 60. Compared to benefits on offer for leaving at 55, one's pension and lump sum grow gently with any additional service - until one hits 60 and the pension / lump sum situation chamges markedly as Backwards PLT alludes to (#36).
Point is - it would appear advantageous to accept the alignment offer, and nearer to retirement age calculate if-and-when one will breach whatever the prevailing LTA figure is at the time. Should one breach the LTA figure before reaching 60 (and for Flt Lt PAS it'll be pretty close!) then a 6-month PVR would still be an option, having served >30 years.
Unless, of course, I'm missing something! If any of the wise sages on this forum do spot a flaw in my logic, I and my colleagues would be immensely grateful if you would point it out.