IP Convergence: Beyond VoIP, Beyond Cost Savings

I am looking into MPLS networks for video conferencing and like Global Crossing's international connectivity.  The people at Masergy tell me that they are the only carrier with MPLS at the core.  They tell me that for video conferencing and Voip, their network is superior to anything else out  there.  Can you tell me if this is just sales hype.  My understanding is as long as you have Classes of Service and QoS, the networks should be comparable, assuming that the number of hops is comparable.  Where can I get more information about the technology of the GC MPLS network?  Besides the type of online tools that are available by a carrier, how does one compare MPLS networks

Thanks!