[Brightcolours]

my 750D has a great sensor, nothing to complain about, however it has 2 shortcomings:

it has no AF microadjustment, in video mode and whwn shooting moving subjects its AF perfornance is poor.

I can live with its viewfinder.

will getting 80D solve those issues, is it worth the upgrade ?

If the AF is poor in movie mode, which lens are you using? Canon's video AF is the best at the moment, with smooth transitions and little hunting, provided you use a lens capable of that. The non-pancake STM lenses are the best. The 80D has similar live view AF., so you better look at an STM lens for this purpose? Or the excellent micro USM lens.

 

You should just have the 17-55mm f2.8 IS USM calibrated instead of trying to rely on MFA, since MFA values for different distances and focal length can be very different. MFA is not a solution in most cases.