By that logic before Sandy bridge was released no one could use any features of pfSense other than firewalling?
You need to qualify that statement with a bandwidth requirement. Clearly if your WAN connection is, say, 10/1Mbps you can easily use a Alix board and have plenty of cpu cycles spare.
Indeed I have a number of Atom 330 1U pfSense boxes in the wild running squid, squidGuard, ntop, etc, and they are great performers.
The CPU requirement depends completely on the amount of throughput you need (in PPS, or more generally, Mb/s), along with the number and type of services you want to run.
Sweeping generalizations like that really aren't helpful to anyone.
True, I stand corrected
Probably the number one reason is that you can build a completely passively cooled Atom system quite easily as it's maximum power dissipation is low. Although the average dissipation of a Sandy Bridge cpu is similar, perhaps even lower, the maximum is far higher so you must allow for that in your cooling solution.
Yes, but can also be done with a SB setup. I still think a SB setup _now_ is a better choice.