2x 250watt HPS/MH or SINGLE 600watt HPS

The title says it all.

I am currently running a 600w hps in a cool tube, with co2 and A/C all in a tent. I'm getting good results with this setup but I've been hearing a lot about the benefits of having both red and blue spectrum even durring flowering.

I don't want to up my electric bill to that of a 1000w, or i'd definitely just add a 400w MH to the whole setup, so i'm left with a possible downgrade to the system. So I guess my question is do any experienced growers out there want to way in on my options:

1 600w hps
250w mh + 250w hps

or maybe even

600w hps + 150w mh

or maybe a 40w hps + a 250w mh?

1k for both! 2k all the way.

Ha, but in all seriousness, what about a 400w HPS and a 250w MH? Or vice versa.

Adding a 150w MH would only raise your electric bill 5-8 dollars a month, would give you a good amount of the added blue spectrum you want and let you keep your current 600w HPS up and running. Sounds like a win-win to me.

Check out Ceramic Metal Halide bulbs. They need a magnetic ballast to run but output a spectrum that's similar to MH + HPS combined.

I wouldn't advise downgrading the 600W to two of something else, for light distribution and efficiency reasons.
Going with 2x 250W would give a larger light distribution, but much less penetration than the 600W; I would think buds would be smaller (of course it's 100W less...)