Added years is the route I took when looking to boost my pension as a relatively 'late joiner' after 4 years at university. When compared to most, average stock market returns over the past 5 years or so, the idea of being able to bump your guaranteed pension up by an index linked amount each year seemed quite a good deal.
However, I will be very interested to see what happens to AVCs under the new scheme. I am hoping that they won't be massively effected, after all, extra years are just that, so I would hope be applicable to all schemes. If not and they decide to close the AVC route under FAPS, I would hope to get a refund of contributions paid so far if they are not going to honour them.
Out of interest, and related to some of the earlier comments about moving to AFPS 05, one comment from an FPS presentation I attended at the time immediately came to mind about 05. It ran something along the lines of "think very carefully before you elect to change schemes; if in doubt, you should probably stick with what you have now. If you change and it proves to be the correct decision, the benefits will be far outweighed by the potential losses if you change and it proves to have been the wrong choice." A little bit of better the devil you know, but it was enough to persuade me to stay on 75.