One more thought on the deadspot...

Think of it this way: what major muscle group is directly enacted in dragging your foot through the deadspot of the pedal stroke? Probably your hamstrings, and inefficiently at that. By trying to get rid of the "whirr-whirr-whirr", all you are doing is gearing down so your cadence increases while decreasing your pedal force in the power portion of the stroke and increasing the pedal force through the deadspot using a group of muscles which have little leverage to make that motion. FTP rises simply because you are one of those who benefits from an increased rpm.

A better plan is to focus on the power portion of the pedal stroke where you have the quads and the glutes working with good leverage and increasing your coordination for recovering your foot as it rises at the back end of the pedal stroke so there is no pause at the bottom. A "dead spot" means a dead spot for power production. This doesn't matter. What you don't want is an actual pause in motion at the bottom of your pedal stroke which is what people refer to as a "choppy" or "square" motion.