If for some reason the rb2011uas-in does not work (be very careful with your rules), then the RB1100AHx2 would most certainly would be powerful enough.
What he said. I am running a RB2011UAS-IN with Verizon FIOS. I get 50/10 and when running full throughput I max out at 25% CPU. But if you are going to run a lot of firewall rules, etc… you may run into a problem. I run a fairly minimal ruleset.