PaulS wrote:........ I noticed that by dropping the seat my knees have moved about 20-30mm forward of KOPS (it was bang on with the higher seat). I cannot move the seat further back, and already have a layback seat-post. Maybe that makes my toes dip - or maybe not. ...
Dropping the saddle 30mm with a seat tube angle of seventy-something degrees will move your bum **back** forwards a few millimetres. Thats not enough to move your centre of mass much, if you want to determine your saddle setback by the balance point method.https://www.stevehoggbikefitting.com/bikefit/2011/05/seat-set-back-for-road-bikes/
Of course most of the change to KOPS is because your thigh is closer to horizontal and your knee further forward.
If you watch the pedalling action of the pro. peloton, they all pedal toe down (these days). I think thats a by-product of the continuing search for an aero position; the rider basically rotates round the pedal spindle, the bars go down and forward, the saddle goes up and forward. Ordinary mortals who try to ride in that position (with ordinary power output/core strength/functionality) find too much weight on their hands.
The reverse is also true, in my experience its easier for riders to "get their heels down" if the saddle is well back.
As you say, its possible you have "learned" to toe-dip with your recent high saddle...you may "forget" in time, I guess.
**EDIT....that should read forwards, obviously.