The "accepted" wisdom seems to be that a 29er has better rollover whilst 27.5 is more manoeuvrable. I do wonder if most who promote that are a ctually more experienced on analogue mtbs rather than EMTBs though.
Firstly, I think you need to be a fairly long term and experienced mtb er to genuinely state that you would notice a big difference between the wheel options, especially when so much else about the bike is also an integral part of the way the bike performs.
Secondly, any difference between wheel sizes is going to be more apparent on certain types of terrain and the more radical and fast the ride the more likely most riders may feel a difference.
So tight and twisty singletrack may feel easier on a 27.5. Rough and rowdy descents may feel less aggressive and challenging with 29er wheels but harder to control.
I say may because what tyres are being run and at what pressure can also make a big difference in either scenario.
I have (

had) both a 27.5 bike and a 29er. Personally for longer adventure rides, flowing singletrack and relatively mild fast decents I would chose a mid travel trail biased bike on 29 wheels. For rough gnarly steep and/or techy descents I would chose a longer travel enduro biased bike on 27.5. You will note that my preference is contrary to how I described the potential/accepted wisdom scenarios a bove. And there lies the quandry!!
Others will of course have different preferences!.