With the pool difficulty at 1024, this should also lower the bandwidth required on the user side as well correct? Most likely setting up a rig "farm" on a farm, and the best internet they can get is 3Mbs. How many mining rigs might this support?
Stratum bandwidth usage is pretty low to begin with. Submitting work less often lowers that number even more, but it hardly matters at this point (I saw someone mentioned 1kbps per rig). You can easily calculate how much traffic goes through your rig with and without cgminer running and get your own results. So yes, for a single rig probably even a dial-up connection will suffice, for a multi-rig setup - a DSL line.