Nate just said much of my 2¢, but I would add that the third requirement is enough dedicated core members that will commit to working their European butts off to make a meet come together. There is also the question of location even within the EU. The Spain, Netherlands, Italy and UK contingents get together occasionally but where would all of those people want to hold a meet? Would some people of each group be involved? How would they coordinate vendor/press/member participation? The cost of these meets is substantial and the vendors primarily foot the bill, but the fact is that vendors will not take a risk on a small turnout and it would be very difficult for US vendors to bring a real demo to the EU.
I'd LOVE for this to happen, and have dreams of attending meets in all three of the above locales some day, but much more groundwork would have to be laid before it could happen. As I said in another thread, more non-US folks need to make the trip to the [Inter]National meets to build momentum and support for having one outside the US -- even in Canada, although that would be the easiest "international" location of all.
The time differences make some of this difficult, but JP#s suggested that we just do a coordinated international meet weekend. The US, EU, Canadian, Asian, etc, meets could all take place over one weekend, but that would mean some people would have to choose which one to attend and some vendors might be caught up in that same choice.
For now, how about we just commit to get as many people as possible to commit to wherever the next International Head-Fi Meet is held? We can plan for non-US events together in person.
