While the device may be most appropriate for high usage/heavy traffic midsized and larger businesses' demands (and budgets: the small business version, GateDefender Performa SB starts at close to $2,000), the GateDefender's approach is worth considering.
That approach includes cloud-based management that gives a single view of company-wide security, antimalware and antispam tools, content filtering, decryption/encryption for SSL scans during HTTPS sessions, load balancing and "the ability to selectively block IM/P2P/VoIP/Spotify communications that are known to critically impact bandwidth consumption."
Rolling P2P, music, VOIP and other heavy bandwidth productivity lowering activity monitoring into the appliance's capabilities puts teeth into employee usage policies. Restricting employees' P2P and other high bandwidth usage not only frees up your capacity (and their concentration) but also cuts way back on some of the riskiest procedures your employees may be engaging in.
Not cheap, and not for every SMB, but, as noted, worth a look if you're looking at hardening your perimeter defenses -- and tightening up your defensive posture within them.