I think the practical queation depends on the individual. I have a 1977 Islander that has the origional wiring which none is tinned or shrik wrapped. All seems to work fine other than the occassional bulb corrosion.
I have had to replace some wires where previous owners had jerri-rigged added electrionic items. I chose to replace the wire rather than leave it in the state it was in using automotive stranded copper as it was compatable to what was in the boat. Has worked great with no issues.
The practical would be how long i planned on keeping the boat. The origional wire has lasted 31 years. I doubt i will keep her more than another year or so as i would like a larger more bluewater capable vesel.
If was was going to keep the boat for a more longer indefinate period of time i would probabily opt for the better qualiy. The optimum meaning you get what you pay for and the tinned, shrink wrapped is less likely to offer problems although the regular copper stranded will work. Even old light cords.