I've previously run a test FAS2240 with 9.0 with only a single 1GbE link used for cluster networking - but it was for testing only. So I can say it works, but it's not supported or recommended.
The major concerns are that a 1Gb cluster link with a 10Gb uplink may have significant issues with indirect access (ie, LIF on node 1, aggregate/data on node 2). I don't believe there is any link weighting possible with cluster networking - so using mixed speeds would not address this adequately, and switchless clusters expect only one or two links, so a third link would likely not work.
Our supported/recommended option for this platform is to run it with a single 10GbE link for Cluster traffic (e1b).