Thoughts on 2x covert LED-x 250's for a 4x8 grow tent

I'm pretty new to growing. Currently I'm running a viparspectra 1200W dimmable series. I've recently gone from a 4x4 tent to a 4x8. I would like to grow 10-12 autos at once and feel like new lights would be beneficial. I would like to cover the tent in light with the lowest impact on electric bill. Help please and thank you!

LEDs should be used at 35W-40W per square foot (on average). You want close to 1200 ACTUAL watts to fill that room. (4x8 = 32 square feet. 32 * 35 = 1120). That light is only 520 actual watts.