Split coupling deflects when it clamped to the shaft. How much depends on tolerance in the fit. More important to face a split than a taper. I have no problem fitting a taper with no skim as the fit is by nature self centering. Still best to at least check it, whole lot easier in the mech shop then troubleshooting wobble in the boat.
No need to face solid couplings as I throw those in the scrap bin.
We had the undersized but stock couplers on our boat replaced some ten years ago or so with larger, heavier split couplers. The shop said one advantage of split couplers is they help hold the shaft in alignment better tnan the old, shorter "lockbolt" style coupler.
It's important to safety wire the bolts in the split coupler, too, so they don't loosen up over time.
Man put a skirt on that coupler and I would ask it to marry me, well at least Id ask it to cruise the caribbean with me.