I think it will result in speeds faster than 960kbps. I'm thinking there's something wrong with the ethernet port or some sort of bottleneck somewhere while using it. But I'm not in front of that iMac so kind of hard to troubleshoot.Do you think this will result in faster speeds than a direct Ethernet connection to the Powerline adapter?
The base station will be connected to the adapter and while WiFi speeds are going to be limited by the card in the iMac, I expect it to be somewhat faster. If it's not then that means, aside from overhead, there's a problem somewhere in the networking.