Hi Kev,
Yep, I agree with all you say. The big difference is that in Europe many collectors don't collect to DJ but still collect rare records. That type of collector, (in the main) is in short supply in the US. The travellers in the US are usually travelling to DJ at gigs whereas the majority of Europeans travel but don't DJ. It's a subtle but distinct difference in the 'scenes' in my experience. For instance: are you DJing at Ann Arbor?
In UK there is a LARGE scene of collectors who have no real interest in DJing. But they are at gigs all over the country (and Europe). Hopefully as the US scene develops people will spread their wings and support each other's gigs by simply turning up, but that's way in the future I'd wager. The other main difference is that in the US many 'soul clubs' adopt a musical policy that will attract a broader musical fan. IE. 60s music that doesn't fall into the category of what would be traditionally regarded as 'soul', in order to get a larger crowd at their gigs. Nothing worse than flying 1000 miles, at considerable cost to find yourself sat on yer ass for half the night whilst the "Soul DJ" plays Brian Poole and The Tremeloes etc to his '60s stylee' audience.
The US 'scene' is developing differently to the way the UK scene did (as you'd expect), it will be interesting to see if people stay the course as they get a little older. Good luck on the trip. Good Hunting!