I have used RDM drives with a napp-it VM and performance was reasonable, though I did not benchmark it against bare metal. My hardware did not allow passthrough.
A big warning though, if a drive goes off line and the VM needs to restart, ESXi will not power the VM back on until the missing drive is removed from the config.
If this is anything more than dev make sure everything is well documented and you know EXACT details on where each drive is physically and where it is assigned virtually.
Is it only slog that you want to use by RDM? What is the rest of your storage configuration?