4x4 Grow Tent + Light: 600w or 1000w for flowering?

I'm starting my first SoG in a 4x4 grow tent and am trying to decide the better light 600W or 1000W for flowering.
Cost is about $100 more for the 1000W and I'll need a fan (which I don't need for the 600W). Plus increased kW $

Is the 1000W too much / overkill / unnecessary for that small an area? I can fit more plants (move more towards the sides) with the 1000W, so $ is not the issue.
Can I have too much light (and heat)?
Is the 600W good enough to make those nice hard, big nugs?
(all in soil, all organic)

I'm leaning towards the 1000W cuz I've never had one and can one really have too much light?

Either light you use you will need a air cooled reflector with the exhaust going out the room. A tent is a hard thing too keep cool. I chose 2 1000w hps in cool tube reflectors for my 4x8 tent but you could defiantly use the 600 or even 400. Anything over a 400 will have heat issues(400 could too). key is ventilation. More light more bud!!!!! So no never too much light but you can have 2 much heat

600 Watt Max is my advise. 1000 watts will be way to much heat for that area, unless you have some hard core cooling system. I agree with Budharvester, air cooled reflectors are a must. And ventilation is key.
Let there be light

But you could run something like a 1000w Lumatek. If heats an issue, buy a 600w lumatek bulb and dial the ballast down to 600w setting. At 600w setting, a 1000w Lumatek ballast will draw 665w. A 600w lumatek ballast on the 600w setting will draw 645w.

Looking to put a 1000w in a GL145, and this is my thinking. Would love some more input, been searching all day.

*Basically wanting another small flowering room for oddballs and miscellaneous trial and error.