HI ,
The path selection policy would be by default selected by ESXi unless you install any 3rdParty multipathing software. So physical paths maintained by you physical components. Logical path selection policy maintained by ESXi by default unless any other plugin is not implemented. So the path selection policy that were there for IBM may be different for Dell. You need to check the following:
First check the compatibility matrix for compatibility.
VMware Compatibility Guide: Storage/SAN Search
Second when you go deeper you would notice the default suggested policies by VMware for this particular type of storage
VMware Compatibility Guide: Storage/SAN Search
For example I took EMC and Symmetrix VMAX with FC as storage and vSphere 5.5 U1 as the OS. So it gives me the default values and what should be set if you use native multipathing, so for that the below was suggestion
Attention: Storage partners using ESX 4.0 or later may recommend VMW_PSP_RR for path failover policy for certain storage array models. If desired, contact the storage array manufacturer for recommendation and instruction to set VMW_PSP_RR appropriately.
Unless there is special instruction from Storage Vendor and if you are using the NMP then it should be followed.
To make matters easier ESXi always selects the default suggested one from VMware so if you are selecting the NMP then go ahead with the default policy that it selects. Shouldn't be any problem in that (unless special requirement from Storage Vendor).
For details check:
vSphere Storage Guide
Chapter 23: Understanding Multipathing and Failover
vSphere 5.5 Documentation Center
So probably vSphere is reverting to the default best practices policy. Once you check the default suggested policy for Dell storage you can decide whether it is this or something else.