I don't think the comparison is wrong per se; this actually makes it a bit easier, since you're just comparing one core to another.

The only thing that I think is problematic is comparing a t2 to anything else, since that CPU performance is not sustainable as it might be elsewhere. m3 and m4 (and other instance types @ aws) are not explicitly throttled. (Source: AWS Solutions Architect)

We're running a portion of our workload at Userify[1] on AWS, but not the biggest portion, but this is actually for bandwidth cost reasons, not CPU (even though our workload is almost entirely CPU and bandwidth -- almost zero disk; our infrastructure at AWS would cost 8x more!)

1. https://userify.com (SSH key management)