they are nice to have and if you don't have power trim, even more important to have one...
you do lose a little top end if you have power trim...sometimes if you don't have power trim you can gain a bit on the top end....
but first I would be looking at what is making it lean to one side....is the motor perfectly strain up and down, lining up with the centre of the boat, maybe you need to move the trim tab a bit to compensate for the rotation of the prop..something is making it lean to one side and I would try to fix that first....IMHO