The AKM slant brake works really well, infact too well. I found them to be too effective and pushed down too far for comfort for the VZ58. Major cheek slaps with the folding stock.
The slant brake design is not really meant for precise semi auto fire, but meant to tame full auto bursts. And for a light rifle like the VZ58, it over compensates.
Yes, it does push the POI higher due the gas pressure redirecting the round upwards.
I would not get rid of it, but try it with some bump firing fun and you will see it is a very good device.