Stealth has given way to strength for me as the main consideration in recent years. In some conditions (glassy slow pools where it's near impossible to catch wild trout anyway), fluoro might be better I suppose. Although a more flexible tippet might give you more micro-drag, which is one of the biggest problems I have in these conditions.
But in all the other kinds of water I fish (stained, broken, fast), the possibility of not catching fish is way more tolerable than the big fish breaking off, which happens to me way too often.
I've just gotten tired of it - makes me feel like shit also for leaving a fly in a fish's mouth, and even if I bring the trout to hand, a stronger tippet allows for a quicker fight that gets the fish back in the water quicker.
So, I've been fishing Orvis super strong, which is a nylon tippet, and have been stretching Trico Mike's rule of thumb, trying to stay away from 6x-8x tippet in favor of 5x or 4.5x for dries and nymphs.