overlighting and power consumption.

In my medium closet I'm running 1000w HPS with a dimmable ballast. I was previous running a 600w magnetic with good results and after I upgraded I started to get heat and light stress so I have dimmed it down to 50% and the effects after a month or so have started to reverse but the plants still seem hindered.

Should i witch back to my 600?

The general temps in the area have been hotter than I've had to experience. So will the 600w run hotter/stronger than a 1000w dimmed 50%.

Also just for curiosity which do you think will run cheaper electricity?

You definitely aren’t doing the 1000w any favours by using it dimmed that much.
Putting undue stress on the bulb and ballast for no good reason imo.
I’d switch back to the 600 and if it’s still too hot then perhaps try to sell both and build an led