Okay, I managed to track down a Google cache -
[Link: 66.249.93.104] - which states that both the 525 and 675 have 2mb.
Anyway, I've gone ahead and ordered a 675 for £49.99, and Logitech have already shipped it today. Last time I looked at harmony remotes, they were way out of my price range, so I'm delighted to get a 675 at this price. It's replacing an MX-500.