It doesn;t know to transpose A to Ab if the A hasn't been played yet.
as i said: it just needs to think: everything that comes in, i will let out through the -100Cents door.
it does not need to know an exact note. just put every signal 100 cents(for example) down.
the digitech drop at least has no feelable latency when going down 1 or 2 halfsteps, it gets a tiny little washy when going 3 steps down. i wouldn't use it any lower.