The Nimble best practice is to use a software iSCSI adapter however a hardware HBA will work. Also be cognizant that some hardware adapters provide less iSCSI connections than software adapters and I am aware of a customer that reverted to the software adapter to get to the higher number of connecitons.
According to Nimble support Nimble does not need ARP redirect so you can leave it off. One of my peers recently installed a Nimble array in a configuration that had a Qlogic 4062 ISCSI HBA with hardware initiator for ISCSI traffic. He pointed out that unlike a software adapter dynamic discovery won’t work and you have to use static discovery to pick up the Nimble volumes. Also a vSwitch was not required in this configuration since it was direct from initiator (w/ vmhba) to array target ports.
Hope this helps.
More for Nimble support
"To verify that the correct drivers are in use, flowcontrol will be on by default for ESXi. This can be checked from the ESXi server CLI using the following command.
ethtool --show-pause -vnicX
VMware's page is here and explains how to set flow control for the NIC.
If you can not set flow control for the NIC, or it is not automatically on, it is a very good indication that the driver is incorrect for the adapter/VNIC"