Safe to put in Mercon V in A833?

There's really only two parts you have to protect; the cluster-pin and the m/s nose-pilot. The rest is normal wear; like needle rollers, brass rings and ball-bearings. If you stay on top of the brassring wear, the gears will last nearly forever. If you don't you'll be looking at repointing the clutch teeth. And if you wait still more until it starts jumping out of gear, then you have back-cutting to do. And if you wait still longer then you might be looking at replacing the sliders and forks.
So the point is, stay on top of the brass rings.