This year the winter sale in January and the summer (?) sale recently both had identical prices, and prices which were still a bit higher than I really wanted to pay (as there's me and the missus).
On the other hand, when you consider that they are paid for with 3-4 trips to the Towers, and everything after is a bonus, well, I may take the plunge next year. I was even more tempted after recently visiting the Cornish Seal Sanctuary in Gweek which is Merlin owned and cost us £15 each to watch some seals flop about. Not that I mind, it's a good cause, but it did make me give more thought to the MAP option again.
Also worth remembering the pre-book 50% discount for friends/family for passholders:
"We do offer a discount of up to 50% off of entrance tickets for friends and family members of Merlin Annual Passholders at most of our attractions. Tickets need to be purchased over the phone on 08444 77 4444 (Lines open daily from 9am-5pm) at least 24 hours before your visit."
Although I always get suspicious of 'up to' figures...