UVs do not kill ich, they sterilize it. I have yet to see data on their effectiveness in aquarium settings. Don't think that it will solve your problems. It might help you control a bit, but if there is a bad outbreak, nothing that it can do to stop or even slow it down. Freshwater dip is more stressful for the owner than the fish if done correctly. However, chasing him around the tank is very stressful. You have a solid plan, just go with it. Just be patient lowering the salinity. How are you cycling the other tank?