I was passing through King's Cross yesterday, so paid a visit to the Fourex machine. Very easy to use. It rejected quite a lot of coins, so I had to feed the rejects back through several times and still it inexplicably refused to take a handful of EUR coppers and CHF 2 pieces, but all in all pretty painless. There were a few Fourex employees hanging around helping customers (it was quite busy, with both machines in use when I arrived, and people queuing behind me) - one guy said that CHF 2 pieces are a known issue.

The rate is obviously not outstanding, but I think it's actually very fair for handling all that obscure, low denomination change. I took the option of a payout in EUR cash. As well as Sterling I think they offer USD.

As you can see, they paid

EUR 0.85 for EUR coins (so a 15% commission, probably twice what you'd pay at a Coinstar type machine, if you could find a EUR one on holiday somewhere)
EUR 0.58 for CHF coins (vs 0.86 mid-market rate yesterday)
EUR 0.76 for CHF notes (vs 0.86 mid-market rate yesterday)