Arnold makes gorgeous renders but is slow. that of course is not an issue if you have a high spec machine or better still use a render farm. it can render TFD volumes on the GPU if converted to openvdb. But where it is really useful if you want to use advanced render is as a preview renderer in it’s IPR. Arnold does not need an Arnold volume shader. it will quite happily use the native TFD shader settings, thus the look you get in the IPR will pretty much match what you will get in advanced renderer. So tweaking shaders within TFD itself becomes a lot easier when using the IPR of Arnold.