I can only speak for this one. :)
With a good SQL backend (like a PPro 200 or DEC Alpha 233) you
should be able to handle that no problem. You'll need to figure
out how many ports you have and distribute this over several
RadiusNT servers to do decent load balancing. Even in the
situation of 1000-1 (a very high ratio) thats 800 ports or
over 17 PM3s.
I would recommend a couple of RadiusNT servers for Auth, and
a couple for Accounting. We have implemented similar situations
like this, and it works out really well. ON a DEC 233 with
about 60,000 users, we were seeing auth times of less than 100ms
with all three RadiusNT servers getting pounded. You also have
excellent failover in case anything goes wrong with any one
server.
Dale