These are gaining ground but
do note these HPS/Mh combos do need to be shielded
meaning ensure that you have some protection
from the Mh bulb, by law they need to be sealed
hence the glass covers on Mh lamps
sometimes they go off like hand grenades
with glass everywhere, in the plants, in the walls
and you..!
hence the tubes are the best
that said theres serious shit with RFI leakage in many
digital ballasts, ensure your comes with a FCC certificate
you don't want neighbors bitching at you at 2am
or the ballast screwing with your wifi?
good luck