Anyone have any experience with this VPN Firewall? I'm debating putting this into a quote rather than a Cisco box from a branch office.

No, but we've used the smaller Adtran switches with VPN with no problems. Great tech support!

I have acustomer with a 2300 at the main location and 2100's at the branch's, customer has been vary happy with it.

Strange, I just called my distributor (IG) and they claim the 2300 has reached end of life. Yet, Adtran still has it on their website. hrmm

I'm totally biased, but I'd say to go the cisco route (pardon the pun). Are you looking to implement a large vpn for users, or a vpn to connect site to site?