I do it about once a week. I ride a Jeffsy 29’er and a Capra in 27.5.
I also test rode a 27.5 Jeffsy back to back with the 29’er. Not much difference in the wheel size. More difference in things like tyres and pressures.
If your going to change bikes there are way more other things that will make it feel different.
The other weekend I rode the Climax trail on both bikes, neither was better than the other, but things like geometry and suspension made the biggest differences, wheel size was not noticed.
Also my 29’er has carbon rims, they make the bike lighter than my mates 27.5 Jeffsy on its standard alloy rims.
There is more to biking than 29-27.5 wheel changes.