[danielf]

11G wireless is 54 Mbps.
11N is 300 Mbps, but realistic throughput is less than that.

Homeplugs are worse. My 85mbps plugs (with 54 mbps wifi) give a realistic throughput of 15 Mbps. You probably have a better idea of what the 200 plugs are capable of.

I'm not sure know what happens if you mix different homeplugs on one network. Two plugs that are rated at different speeds will only be able to communicate at the lower of the 2 speeds. Not sure what happens when two high speed plugs communicate on a network that also has a lower speed plug. Having said all that: I've only seen 200 Mbps plugs with wireless, so that in itself may limit your options.