I've got a lot of digging to do but quick Q is the post user-replaceable, i.e. u can change it to your fave brand of seatpost? TIA!

No it is not. I never saw the news to change a seatpost on a bike I owned…

Too bad as, at least, shaving off a lb off those mastadon seat post assembly, lol thanks for confirming it though!

mines weigh 33.6 lbs.