Many strange things about barracuda firewall
Although this decision should be based on your requirements however; you should try to opt for unlimited data transfer. Apart from that you should also check the bandwidth provided by the service provider. A bandwidth of 6Mbps or near that will be perfect for you. Secondly, you should check the Tier Class facility of the company and Tier 1 class A will surely provide you with redundant power, security, continuous monitoring and generator back up. You should also consider your distance from primary backbone; if possible.