With all IPs from the storage target and initiator on the same subnet you will not not have issues with it using all of the paths. If you do use all one subnet you want to make sure that any switches being used are either stacked or trunked to ensure you do not get a split horizon. Multipathing software be it VMware native support, MS MPIO, Linux RDAC, Linux multipathd, EMC powerpath, EQL MEM etc... ensures that each path to the iSCSI target is used. I have personally setup multiple configurations of iSCSI Storage products in both single and multiple subnet configurations.
When the discovery of the array is complete the VMware iSCSI initiator will login to all ports on the array from all VMkernel iSCSI IPs. The only differnce between the IPs being on one subnet or multiple subnets will be the number of iSCSI sessions / paths established to the iSCSI target.
SInce the MD32xxxi arrays have two Raid controllers not all of the paths to the iSCSI target will show Active. The Active paths will be to the ones connected to the controller that currently owns the LUN. To make sure you are making use of all of the paths to the Active controller you will need to change multipathing policy to Round Robin. At the bottom of this Dell wiki page here are screen shots of what needs to be set.
12. To configure round robin multipathing policy using the VI client GUI, for each LUN exposed to the ESX server, change the default path-selection policy to Round Robin (VMware). This enables load balancing over two active paths to the LUN (two paths through the controller that owns the LUN; the other two paths should be stand by).
a. Right-click on the device and choose Manage Paths.
b.In the Path Selection drop-down, select Round Robin.
Before this selection is made, one path has a status of Active, another is Active (I/O), and the other two paths are in Stand by.
c.After selecting Round Robin, two paths have a status of Active (I/O) and other two paths are in Stand by.
d. Repeat the process for each iSCSI LUN presented to the ESX 4 server from the Dell PowerVault MD3000i.