Ballast question

I'm looking at a hps/mh combo ballast and wondering if it is as good as a dedicated hps or mh ballast? Is it just some marketing ploy where they give you a mh bulb that can run in an hps ballast or is it comparable to having both ballasts and it just works with whichever bulb you use?

Basically do I get the full benefit/power when using a mh bulb and then when I swap it out for flower I'm getting the full benefit of the hps?

Also I'm allowed 4 plants in my state, I grew outdoor last year but my entire property is covered in massive trees, and while the sun was overhead during summer and my plants got huge, in August the sun lowered in the sky and was blocked by the trees, only getting 2 hours of direct sunlight, and it only formed little buds, so I'm switching to indoor.

My plan is 4x 50gal trash cans with 4 plants and a vertical 1000w dropped in the center. It's in a large garage 12'-16' ceiling, plenty of head room. If I do a horizontal light I would need one for each plant wouldn't I, and 4 of them would be like $240/mo in electricity? I'm leaning more towards vertical.

All newer style digital ballasts can run both mh and hps bulbs.
There are also conversion bulbs to run in older style magnetic ballasts.
I think your looking at this the wring way and trying to grow mosters inside lol. Doesnt really work that way but hey give it a try and learn a lesson.

Fair enough, yeah I was imagining growing the plants for 6-9 months like outdoor, but I guess the light won't penetrate once they get too big indoor... This was 1 plant in a 32gal trash can on my deck. After this picture was taken the buds didn't get much bigger cause they got less and less light until it was mostly shade.

Now I'm thinking just do 1 plant really well under a 1k watt with a hood, and do the other 3 outdoor even though my yard is shaded. My goal indoors is better buds, and outdoor for quantity. Gonna grab the mh/hps combo light.

Back in the day I tried a mh in a hps ballast and it struck up, I think the ignition is the main difference they both supplied 400w.

A couple of weeks ago I realised that I'd been running a 250w with the ballast set at 600w, that watt meter didn't indicate that anything other than normal current was being drawn.
After thinking about it for a couple of days I thought, the bulb draws 250w the ballast doesn't ram 600w down the cable, but it has the ability to at that setting, but idk anything about electricity except that you can't see it and it hurts.
The 250w light ran for 12/14 days at 600w, I only noticed when swapping tents.

The old school magnetic ballasts only differ in that the HPS uses an ignitor and the MH does not. The old magnetic ballasts had a switch that cut out the ignitor is MH is selected.

The newer digital ballasts can run either MH or HPS bulb and they are the way to go.