I mostly ride old roadie conversion-to-x bikes in rocky rooty dirt trails, but I also have a couple 26ers I take out occasionally when the joy of needle threading a narrow tire through is less appealing than just blasting through like a moron.
The top thing I hate about mountain bikes is they only have climbing gears and have no gearing for smooth flats or mild descents. Puncture resistant tires only make it worse by making it feel like you’re going uphill while descending- just great on a flat rail trail.
If you sometimes like doing fast moron riding in the trails, keep the 29er, and maybe try it out with some used high end <1,800g wheels & nice tires (Conti Kings, RH, etc), and maybe larger touring triple style middle & outer chainrings if they’ll clear the chain stays.