The one we had demo'd to us last week was a Watchguard Firebox x750e. This was able to split the 3 with full control over available bandwidth for different applications and control over the WAN modes, i.e. Spill over, round robin, Failover, ECMP, etc. There are a few other requirements that I had such as file extension blocking capabilities, URL / site blocking, full port control and blocking, P2P blocking to mention a few and the demo covered these no problem. I am looking at comparisons though as obvioulsy need to make a full justification for expense.
Some more information on the site there. 12 servers in all, mainly Win 2003, Exc 2003 used as mail with front and back end servers, servers used exclusively for engineering / design and the usual suspects in relation to purchasing, HR, AV and accounting systems. There are 3 DSL lines going in as bandwidth for larger lines not available in that area, and one lease line fallover. So pretty well set up and wanting to maintain it that way! We usually buy our equipment here, set it up and then take it up in back of car for site there. Certainly do not want to be placing in dodgy local equipment. We are currently using Watchguard firewalls in both HK and China, although increased requirements now mean we need to add this extra firewall there.