Definitely not necessary. As you can see from my signature, I purchased both from my PB. They were installed, and within a month or two, I removed them both. The ozone is a constant suction side leak, as it draws air across the lamp, and the UV eats up the chlorine that I am trying to keep in my pool. So I had to have my SWCG higher than necessary.
Regarding cost, for my PB, it was a $1000 option for both. Which is why I went with them, I figured it wasn't that much, in the grand scheme of things. I just did not do enough research ahead of time. I definitely had not found TFP at that time.
--Jeff