Correct, we have not tested with the IP addresses being on different subnets and the recommendation is to have all the storage controller, management and IPMI addresses on the same subnet (XMS can be on a different network, but should be routable to the other IP addresses). However, if you need to have these IP addresses on separate subnets, I would recommend submitting an RPQ to enable us to evaluate the scenario and provide our recommendation.  To answer your question about the VLANs on eth0 – we recommend that the management and IPMI IP addresses be in the same network, but an RPQ should be submitted otherwise. Needless to say, I will get this clarified in our product documentation.  Just to clarify on a comment you made earlier – IPMI is not going away with 4.0 release. The only change that we did in 4.0 was to enforce the implementation of management and IPMI addresses to be on different ports on the storage controller. With pre-4.0 releases, you had the option of having both the management and IPMI communication happening on the same port or different ports.  Hope this helps.
Are the Management and IPMI IP's/Gateway required to be the same network on a 3.x install? I have heard they need to be on the same network, but have read differently in the 3.x pre-site guide that only talks about them being routable to the XMS machine (which they will be).   Can someone confirm the requirements for a 3.x install please? I have been lucky enough in the past with them all on the same network so this is the first time hitting the requirement for different networks that would be routable through different mgmt. and IPMI gateways.   Thanks. 
IPMI Network in 3.x