Don't need 6v if the resistance is low enough.
The 1.3ohm atty that is on my SB hits at 10.5 watts at 3.7v.
Don't need to bother with inconsistent, short life low resistance cartos/attys when using a good regulated, boosted variable PV that provides consistent, long life power. And you get the variety of any atty or carto instead of being stuck with only low res ones to get the feel/warmth/hit one likes.