I’d say 95% of my local trails (QECP, Kingley Vale, Lordswood etc…) I’m either no slower or actually faster with the rigid post on my xc race bike, according to Strava data.
The other 5%, mainly the steeper stuff with big drops & jumps in, I’m absolutely slower and can tell when I ride them that I’m not in as good a place on the bike.
I guess then, it depends on where you ride and what the trails are like. Like so many things in life although generally it’s abgood thing to have a dropper it’s not always the life changing thing it can be made out to be.
My Di2 battery is in the seatpost though so I’m reluctant to change on that bike.
I am currently rebuilding my old Parkwood frame up as a winter/play bike though & that is getting the dropper put on it for sure.
I was an early adopter too; Maverick Speedball way back in the day was my first dropper, before CB bought the license for them…