I have an 1895 in .450 Marlin and it simply rocks!!!
The open sights a good to go to 200 meters IMHO and if you don't like the factory set up, XS makes a great aftermarket, high viz ghost ring set up for them. I have it zeroed about 2-3" high at 100 which is dead on at 200. I wouldn't stretch it's legs too far beyond that as the thing turns into a bit of a rainbow. That said, it is nuclear for smashing through brush and cover to get to that deer's boiler room in a circumstance where a clean shot is not going to happen - try that with your traditional high speed, longer range, deer caliber.
I agree that scoping it would be a crime - keep the scope for another toy that warrants that can actually put the optics to good use for the money you have invested in them!!!
Last but not least, the 1895 (especially with an 18.5" barrel) makes for a nice bear defence carry gun and is also great to 200 meters for hunting bear, moose, and elk.
I'm about to head out right now in search of a muley buck, and white-tailed buck, or a white-tailed doe (hopefully all 3!!!) and my .450 Marlin will be riding very close "shotgun" in the truck!!!