Either my flies are getting better, I am getting better, or the fish are getting dumber, but my catch rates have increased since I switched over. The ONLY time I have seen a slow take is on a dry fly. Most nymph takes IMO are a slash take so I doubt seriously they see the knot.
Who knows, maybe trout are far sighted. Why else would they hit my flies? HA!
Besides I don't break off at the knot, it seems it's always the tippett, or at the triple surgeon's knot.
I am a great admirer of spectator sports, especially on television; it keeps the riffraff off the trout streams.