I don't think a dedicated line completely eliminates noise. It eliminates variance caused by appliances and such, but the line is still subject to interference from RF, EMI, and other things. The Noise Hounds are simply noise filters, and I've used them to good effect (I use two of them on my audio system, which currently has no other power conditioning)...quite honestly, I see more effectiveness with them on my TV signal than I do in my audio system. (disclaimer: I am a Blue Circle dealer)
You might want to see how much noise you have on your power line by picking up (or borrowing) a Noise Sniffer from Audioprism. With your other power conditioning equipment, you might not see that much benefit from the Noise Hound. On the other hand, you might...