If you could find the time to appear at that event, it may be more productive it coincide with the Silicon Valley Comes to Oxford event held in November, or FOWA London on 3-5th Oct, both of which you have presented at in the past.
As one of the founders of http://www.44con.com/ I'd be happy to chat about making this happen. We have everything we need geared up for this and could do it as a free or paid for conference.
What about Paris? I'm hearing from neutral sources (not me, I'm biased) that Paris is ahead of London in terms of startups. I actually was surprised to hear that.
I understand that the language barrier can be stressful for Americans. London is therefore the default choice.