I'm in the midst of planning a data center refresh. We have a pair of Cisco 6509-E's in a collapsed core configuration. We want to reduce spanning tree so as to use all uplinks from the closets. We also want any kind of failure of one core switch to be as quick and painless as possible to the network. We can upgrade to Nexus for FabricPath, Arista for MLAG, and Avaya for SPB at our core. My question, has anyone used any of these technologies and can attest to their effectiveness. All companies try to say their tech is better than the others but without having actual hardware onsite I thought the next best option would be to ask anyone who has actually implemented the above tech. From my side, it'd be nice to stay Cisco but they are pricey and you hear a lot about their current line of Nexus not being as fast as it could be. Arista's option isn't anything new (MLAG) but they are supposed to have the fastest switches around. And Avaya's SPB is very new and seems to have bugs here and there, as well as have features that are "coming", whenever that is.