Multicast Rate: 2 Mbps or 11 Mbps...which setting?

I am trying to maximize the speed on my network. I have upgraded from 1.5 Mbps to 6.0 Mbps with my ISP and I have changed a setting in airport utility to reflect 802.11g compatible only. These changes were based on helpful posts here so I thank all. I have one last setting (Multicast) I have a question about that I have read conflicting opinions on so I am posting here to get a definitive answer if possible. I have a WDS network setup with an old UFO-like airport extreme base station as the main station and then 2 airport expresses set up as the relay and remote stations. All 3 are older and don't have the 802.11n standard. I use 2 powerbooks, 2 iphones, and 2 ipads on the network not all at the same time. I currently have the airport utility setting to be 2 Mbps on the multicast setting...would it make my wireless experience faster if I changed the Multicast setting to 5.5 or 11 Mbps or does it not make a difference? Thanks much.