I've got Silver Thread in 6, 8, 10, 12,14,17, and 20 now that you mention it. Lol. CX Premium is better on spinning IMO, I was happy witht he Silver Thread until I tried the CX Premium. I still like Silver Thread for my casting mono apps.
Yes, I have directly compared Fluro to mono with a FB in cold water with subtle bites and I absoultely felt more bites and caught more fish with the fluro. I wish it weren't so. Darn stuff is expensive.