A 190 SL was my first car. I drove it every day as my main transportation for many years all year around. I never hesitated to jump in it and head out on a long trip.
Just remember that a 190SL is a full model generation older. A lot of driving improvememts were made in the model generation between the 190SL and the W113. They are different animals and different technologies. It is only natural that the newer generation should be improved, and more drivable. On the other hand it is only natural that we can appreciate the quality, hand craftmanship, simplicity and inovation of things older. Newer automobiles, naturally should be safer, faster, more fuel efficient, and generally be more drivable than previous generations.
In a 190SL a fan was not supplied for heat or defrost on the passenger side of the car. The single speed heater motor for the drivers side was barely adequate. I remember those zero degree mornings so well. The windshield wipers were marginal. It had a 20 amp generator for power. The four wheel drum brakes were the latest state of technology with the front dual cylinders. The frontr drums were aluminum finned with iron inserts, the very wide aluminum shoes were self adjusting. Most had the ATE vacuume booster. Marvelous braking, and the state of the art for drum brakes at the time. Very complex and seldom correctly fixed these days. Yes, volumes have been written on the complex carburetion. It was not really a defective design, just so complicated that few can mount them correctly and put them in good running order these days. The huge steering wheel was meant to make up for the lack of power steering in the heavy little roadster.
One generation of Mercedes eariier, (the 170's) cabin heaters were an option all together! And during the 190SL era other sports cars were much more basic with snap in side plastic windows and put-together soft top kits. The 190SL was so refined and luxurious for its time that many refused to consider them a "sports car" in those days.
The later model generation W113 is more drivable as it should be. Which is best for you? It is like comparing a Picasso to a Michelangelo !
