UGH voltage

I have spent some time researching the archives on UGH's.  Everyone seems to
agree that both versions (low wattage .1-.2 watts/l and high wattage .5
watts/l ) are very benefical to plant growth.  However, the issue of long
term stability with the low wattage approach remains in question.   As many
of the comments on this topic are somewhat dated (1994-1995) I'm curious
about the current thinking on this topic.