On the very rare occasion mine go off, I haven't noticed a delay, and I've been right on my rods.
Have you seen any of the underwater films?? There is always a bit of delay from the fish taking the Bait to the alarm sounding.
Sorry, yeah! The no trace beads! Thanks mate. I agree with the above comments about not dropping the lead on a helicopter set up. I want the weight of the lead to assist with separation of the leader and Hooklink in the event of a crack off.