I have a Thudbuster ST on one of my bikes* and I love it. It allows you to remain sitting over bumpy stuff, reduces fatigue (great on all-day rides) and allows for the odd “Oomph!” moments when you were not as far off the saddle as you thought.
Down side is weight (less than a regular seatpost + really expensive rear air shock….let alone pivots / swingarms!) and odd looks. Oh and cost but again its much less than a full sus frame (or even a shock!)
Over all 10/10. I might even get the longer trave version for the other bike.
SSP
* a fixed gear MTB where standing up on the pedals is not the same option on downhills as a bike with a freewheel!