Should i?

Currently running a 400w hps while vegging. (My MH burned up, waiting on new one)
4 inch inline in a 2x3x5 foot tent.
The MH was WAY hotter.. Even though people say hps is hotter.
Do you think I could run a 600w hps in flower?

Overkill in that space. Get a 315.

Or this - http://timbergrowlights.com/model-2tl/

Or this - https://horticulturelightinggroup.com/collections/diy/products/260w-qb-led-kit

Yes you can if your ballast will fire a 600w lamp. I dont know what youre running to say yes definatly. I agree with Johnny that its overkill for the space. If you have space, and a few dollars a 4x4 is pretty affordable. You could think of upgrading your area. Then youd have a small area for side projects, and upcoming grows. Just a thought

I'm running a 2x3x5 space right now as a tide me over until the new house is done and i can tell you for certain that a 600w hid of any kind is so overkill in that space. The cmh and led options that Johnny recommended will serve you much better in a space that small.

Thanks for the advice and help guys! I'll hold off on the 600w til I can afford a bigger tent and everything else I'll need.