Before you calculate the "value added" to your pension you might want to consider that while the payout will increase 2.5% of your base pay for every year you stay in, you also have a limited time to receive it. Assuming the average person would be able to retire at 42 with a life expectancy of 82 years you have roughly 40 years to receive the retirement. Every year you delay it by staying on AD, you lose 2.5% off the total.
There's a lot of assumptions. If you are older at retirement (or are in poor health and have a shorter life expectancy) the pension is worth less vs if you could retire at say 37 and expected to live to 100.
If you look at buying an annuity. There's also a lot of assumptions in calculating the "present value" of a stream of future payouts so you can fudge the results in either direction by tweaking the numbers and then checking the actuarial tables to factor in life expectancy.
Bottom line I dont value a 3k annual increase to my future retirement at 78k cash in hand.