I would add though that some HPS lamps are prone to failures in e-ballasts.
I think hortilux have had issues with e-ballasts.
Ushios tend to be a USA favourite.
Depends where you are in the world though,
With my LUMATEK 600w dimmable e-Ballast i use a FUTURE TECH 400w MH and a SUNMASTER DUAL SPEC 600w HPS for veg and flower.
J