im using on my a7ii.
what kind of advise u need?

unless u doing really2 close up
sharpness is quite good & with the 1/3 price of the batis, a lil bit of post processing should be enough.
but on a7ii , i cant rely on the peeking that much at f/1.4 
quickly magnify zoom is faster even in event/weddings 

sample

at wide open the samyang may be less contrasty than the zeiss pop (zeiss is known for their micro contrast and great IQ glass)
the 1st pic initially was low contrast due to the flare
but a little pp on lightroom can fix

u need to worry bout CA at wide open
that's it for me