Firewall – Any recomendations

Has anybody use Symantec 5420 appliance? I am looking into the following firewall applainces:

PIX515
Symantec 5420
Sonicwall 3060

I have about 200 users. I am currenlty using WAN/LAN AND DMZ ports. I heared that 3060 has a bug in it and symantec 5420 is not a true stateful firewall. Cisco finally came out with PDM and wondering if am better off trying PIX515.

Any recomendations?