I am not network savvy and I just upgraded to Google Fiber from a Comcast 250Mbps connection. I have an RB2011UiAS-2HnD-IN and was thinking it would be sufficient.
Yes, you should upgrade. For sizing, go onto the products page and look at the device "Test Results" tab, specifically the 512 byte packet 25 ip filter rule routing performance. That will give you a good general idea of the real world maximum throughput of your device. For the RB2011 it shows 244.1Mbps, which shows that it was just fast enough for your old service.
2011performance.JPG
In some cases you can get a little more (with fasttrack etc), but for a reasonable configuration I would agree with sizing the RB2011 for a maximum of around 250Mbps.
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