i have vintage singers including a FW and i have the newer quantum and i do not see a difference in stitch quality and it sure is nice having all the modern features.
i never sew on my vintage singers but i do use the newer quantum from time to time.
if i didn't have my day to day juki i would not having a problem buying this machine.
i don't know if the quantum will be here 100 years from now like my vintage singers but it doesn't matter to me since i never sew on my 100 year old singer any way.