I'm no experienced prop expert, but for the last 2 weeks I have been researching companies, some need a series 7 , some don't
I will tell you that you left a pretty good one off your list
BRIGHT TRADING
Don from BRIGHT TRADING e-mailed me about 10 times, answering a ton of questions for me even after I told him that I was going to try to find a place that didn't need a series 7 so I could try it out without the expense of the license and the time it would take to get it before I could trade.
Not many people will help you like that, especially when their in business and your asking about the compitition, most wouldn't even get back to you, so don't leave out BRIGHT TRADING you would be making a mistake
don't know about ECHO, but they were pretty nice guys too, and theres a thread about them here somewhere
Good luck to you, ask a lot of questions