I've got a 3100, no USB. No complaints, it's on all the time, feeding a Linksys BFSR router, which feeds my edge switch....
My biggest complaint is the cable company personnel and their operating procedures. The system has been down twice in two years. Both times it was in their system or infrastructure. They still sent out some dweebs that tried to convince me that the inbound signal was 12db too hot (I don't have cable TV, I'll eat liver before I ever subscribe to cable TV). Their solution was to take a five-way splitter, connect the gozinta and gozoutta..and leave the other three ports open...dribbling data all over my uility room floor (they didn't have any attenuators). When they left, I removed their "Fix" (idiots), called in again (cause it still didn't work), and after they reset something, it was OK. They billed me, I disputed it, they ate the charge.
The data guys don't work & play well with the infrastructure guys (the cable TV guys). They wonn't believe the problem is on their end untill their "techs" have a shot at FUBARing my computer(s). It's actually not that much grief, and I get ~ 3Meg down/128K up 98% of the time according to DSLReports.com (small neighborhood).
Good luck, have fun, high speed is a wunnerful thing.
Scott