a 600 is actually the best lumens per watt you can get, and the difference in heat is less than you would expect. I would DEFINITELY get the 600, and an air-cooled hood to go with it.... EXCEPT:
The only thing is that it is a big light for your space. How TALL is your space? Will you have room to set up the exhaust correctly? Do you have another space that you could use instead, that is 4x4 feet? That's the correct 'footprint' for a 600.