IPFW+Dummynet Capability

[Kazi A. Sharif]

Hello Guys,
I was planning to install a heavy duty bandwidth manager for my ISP. I 
went through some documentation and installed IPFW and Dummynet in 
FreeBSD 7.0. Before I spent so much time on this I need to know the 
limitations that are already noticed:
1. If we compare IPFW+Dummynet with Allot or Emerging Technologies 
Bandwidth manager, how efficient is the IPFW+Dummynet?
2. Is it possible to control/throttle 800/900Mbps bandwidth using 
recommended hardware?
3. Can I shape bandwidth for 3000 to 5000 clients with Dummynet where 
concurrent connectivity would be 2000 to 3000?
4. If I can serve 5000 users then what would be the performance 
decreasing ratio?
5. If I can not use Dummynet for my requirement then what are the 
recommendations?
Thanks in advance.
Sharif