Thanks MooncupGoddess "they valued it very highly, only for it to sit on the market for months."
That's what I suspected. Felicity J Lord valued it much higher then three other EAs we met, but they're the only one who wanted to tie us in to a 16 week contract! (The others are asking for a month's commitment only).
In the area we're in, demand is high for flats, and they're going in just a week or two rather than months. (I know this from recent experience of neighbours as well as the advice of EAs). So that begs the question what on earth do FJL need 16 weeks for? Unless they've overvalued it to get me on the books.
I asked them today actually if they'd consider cutting the weeks. They suggested 10 weeks, and the EA said it'd take a couple of weeks to get everything set up. (Set up what?!!) Considering the others are promising to sell it within 2 weeks, I think I have a definitive answer now! Also I'm a bit bemused by them posting the valuation letter - all the others emailed it to me.
I've heard good things about Keatons, actually, and the woman who came to visit us seemed very professional - I didn't feel she was doing a sales number on us - and she was recommended to us by a neighbour.
We've decided to go with an internet agent after all (housenetwork.co.uk , they charge a flat fee of £600 rather than a commission), but if that doesn't work we'll go with Keatons.