>> We'll be supporting several thousand clients, all receiving realtime updates to their browsers at a rate of 6-40 per second. <<
Do you mean that the data changes up to 40 times per second, or that the users *screen* has to *change* 40 times per second?
That is faster than most *movie* refresh rates, and movies are usually buffered and not customized per user.
Hell of a requirement.
I suggest you look into missle guidence techniques or something. You are gonna need high-end stuff. I doubt off-the-shelf browsers can cut it.