In case you hadn't realised: The big advantage of the 2610 over the Quest is that it has removable/user upgradeable memory in the form of Compact Flash. Large CF cards are dirt cheap now which enables you to fit the whole of Europe onto a 2GB card. It's screen is bigger and I think its processor a little more powerful but other than that there's not a great deal in it.
The European model of the Quest 1 has 256MB of internal memory which is soldered to the main board, this is definitely not upgradeable in any way (the American version of the Quest 1 only has 128MB so be cautious if buying used). Of the 256MB 243MB is available for you to upload mapping data to, this will comfortably fit the whole of the UK and a chunk of the North French coast. When touring abroad you will need to load suitable mapping for your trip from your PC overwriting your UK mapping which you will then need to reload on your return. Due to limited and fixed memory ambitious tours on the continent may see you not having enough space to load all of your trip to the Quest. You can do Spain and back but any circular tour, say getting there by the west coast of France and then back via Austria will be too much.
I have a Quest and am more that happy with it (purchased on eBay for £130 over a year ago). With a young family, busy job and next to no disposable income my prospects of big Euro touring are limited to nowt so it suits my purposes very well.