I was using USB2.0 direct from the camera, and it was painfully slow on my 5d2. Don't know if a dedicated card reader would help, but I have USB3 on my laptop, so got the Lexar USB3 card reader, and it's fantastic.
In terms of raw bandwidth, USB3 > 1Gbps ethernet > FW800 > USB2. In terms of actual usable bandwidth, it's probably a tossup between 1Gbps ethernet & FW800 since the MAC + IP + TCP takes up some overhead, and if you have a cheapo switch it may not support full wireline speed well and might fall short a bit.
The Lexar 1000x card can theoretically do 150 MByte/sec, let's say it gets even close, then that's ~1200 Mbit/sec which exceeds 1Gbps ethernet & FW800 by a decent bit, especially when we throw in protocol overhead. USB3 can do a theoretical ~4.8Gbps, and even with protocol overhead you're easily going to have enough to read from the Lexar card. However, we now have to deal with how fast your local disk can write the data out. I'd guess that unless you have a RAID0/5/0+1/1+0 array or a fast SSD you won't be able to write it out fast enough.
That's not to say I wouldn't buy the Lexar reader if you have USB3, but since you don't that'd add some more cost and pain. If you can live with a somewhat slower transfer, stick with your current USB2 reader, otherwise go for the 1Gbps ethernet or get the USB3 card & reader.