Our central office has a VPN 3005 and a PIX 515. The VPN 3005 is the hub for 7 branch offices/spokes - each of which has a PIX 506e. The PIX 515 serves as the firewall for the cental office.
From what I can tell, the ASA devices don't suffer the same routing limitations that the PIXs did. It looks like the ASA will route traffic back out on the same interface that it came in on - for VPN purposes (I don't want a meshed VPN - all VPN traffic should travel through the hub). Would the ASA 5510 give me the capabilities of both older devices wrapped into one single new device?