I have had my 1948 3100 for about 5 years and finally broke down and switched her to 12 volts. I got stranded last year at a local parade and the kids were very disappointed. I feel that going to 12 volts will be better for reliability. I know that if everything is maintained properly the 6 volt system works just fine.
My issue is that this is one of a few cars I have and do not use it consistently.

This is an original truck that sat as a decoration for decades in front of a body shop that I rescued. A testament to "Made in the USA", I got it running after sitting for 40yrs with not too much effort (maybe a day or two in my garage).

I will obviously keep every 6 volt part I took off and can switch it back whenever I want.

The faster cranking speed is a big help when she has not been started in a month or two. I try to be a purist and wanted to keep her original but I finally broke down after many disappointments of not being able to get her started. The last time (2 weeks ago) I ran her for 20 minutes and shut her down and then she would not start 15 minutes later....SMH

I do feel a bit guilty...

Frank
1948 5 Window Chevy 3100 an absolute rescue that is now back on the road
1953 Buick Super 1 family owned since new
1956 3200 Big Window
1985.5 Mustang SVO
1986 Mustang SVO