Been looking at the RRA wadcutter pistols.(maybe a Christmas present to myself

Question is, frame mounted scope or slide mounted scope ?
RRA has what looks like the ability to mount a scope on the slide if needed, but also has open sights mounted on the gun.
Reason I ask is that I will be using open sights until my eyes get worse and then I could mount a scope on it if needed.
Just like the M41 that I have coming(got that for myself as my birthday present

The M41 is drilled and tapped for a scope, but have the option of using or not using it.
Can these scopes really take the battering when mounted on the slide ?
What would be the best scopes for this application while mounted on the slide ?
Thanks.
Clarence;