The first two have switch chips so traffic between devices in the network are switched and do not enter the CPU unless it is router traffic to the outside.
The hEX S is ............ I have two but never got it switching directly. I happens all in CPU/Bridge and the SPF reduces the overall speed of the ETH to 1Gbit/s and the SPF takes the other half of the 2Gbit/s. However it is a nice device with an option to have a SPF at a cost of speed.
If you seek also Wifi then the AC2 and Chateau are very nice. The Chateau is a brandnew model.
Problem is I need 4 interfaces. The "cheaper" device I've found is the CCR1009-7G-1C-PC (8 interfaces) at $425.
Or I could use VLAN trunking at the cost of a lower bandwith.