I'm sort of balancing the two too - Quest II and 2610, that is.
Quest II has pre-loaded EU City Navigator, you'd need to buy a 2Gb CF card on top of the 2610 to hold that much, I think. The Quest II has the built-in battery if you want to use it off the bike, whereas the 2610 requires a power connection (you can get non-Garmin packs to power it off-bike though, I think).
The 2610 has a bigger screen too.
I think my final choice may be down to a 2610 if I can get one from the US (what difference does the base map make if you have the whole of the EU on a CF card?) or maybe the new 60CSx (has a faster, better chip for acquiring satellites and takes a microSD memory card that are currently up to 512Mb, with 1Gb and 2Gb in the pipeline, apparently, but it doesn't have voice for routing).
Not sure where to go on this, but luckily I'm not planning to buy for a while so I've got plenty of time