I have also sailed on both steam and motor vessels. My experience is that I had more problems with personnel on steam ships and more problems with machinery on motor ships. IMHO the steam watch standers had way to much time to devise jokes on each other. The one joke I disliked the most was closing the DC heater vent. After three days the feed pump would become air bound the both boilers would trip off due to low water level. It took us three black outs to figure out the cause. Of course the miscreant was no longer on the vessel.
The Marine Super that I had my most dealings with told me that my budget on the Marine Floridian T 2 tanker was 80 per cent over time 20 per cent spares. On the Marine Reliance at the time a 6 year old Sulzer Car Carrier my budget went to 20 per cent over time and 80 per cent spares.
It is just economics that Steam Ships are not build. The Steam Plant cost more to build, take more cargo space, require more fuel storage. When I was at school a long time ago a diesel plant would cost about 1 million dollars per cylinder while the reduction gears if you could get a set would be in the neighborhood of 46 million.