Funnily enough I have been considering getting a gravel bike and binning the MTB, so an opposite to you.
As many have stated in here if you are flying over rocks and drops a MTB has the advantage, but then your rides might be slightly slower.
I have been considering a gravel bike for time efficient riding and throw in some road and off road rides and mix it up, instead of going out on the discipline specific bike which I can currently do.
If you are keen on getting a MTB to do what you currently ride and maybe in some more gnarly rides I would advise on a short travel rig, less stuff to go wrong, less stuff to clean and cheaper maintenance.
Most of the bikes we all see riding round our local routes are so overkill it’s unreal, and they pay the price on the climbs.