I noticed a much bigger difference in handling and turning quickness (if there is such a measure) when going from my first MTB to my second in the mid ’90’s, so both 26″. My first had a shorter wheelbase and was very manouverable and ‘quick turning’. My second bike had a longer wheelbase and was noticeably more sluggish, but far more stable at speed. Geometry has a far more powerful effect on this than wheel size in my experience.
I have no problems at all (apart from the limitations my own skill places) on my 29er in switchbacks, slow technical sections or quickness of turning. In fact I’ve just changed my forks and my new forks have a 51mm offset vs. a 46mm offset on my previous forks, and that has had a very noticeable affect (improvement) on the turning quickness and feel of maneuverability despite an increase in wheelbase due to the offset and a 13mm longer a-c length slackening things up a little.
So it’s not as simple as saying just one aspect affects handling on its own. It’s the net affect of a number of things. There are slow turning 26ers as well as slow turning 29ers.