I run a 600w HPS in a small(ish) room with a basic reflector, no glass or even ends to it, 240m2/h exhaust fan pulling from one side of the bulb, and a 100m2/h intake of fresh air at the other side, with another intake fan lower down for air circulation, if i turn the exhaust right up the temps stay within 4-5 degrees c above ambient on a hot day (25c is what we call hot over here in blighty).
Before I added the intake near the light it got up to 40c when it was 22 outside, and I had to keep the light 14" above the plants, now it's around 8" away without burning them, could go slightly closer but gotta allow for growth. This gives me an extra 6" of grow space, which is a lot when the ceiling is only 4' 6".
I've no experience with proper cooled reflectors so couldn't tell you how this compares, though I have heard that plants can grow up to, and even touch, a good one with no burnage. I would guess that then you'd need an extra fan to extract stale air from your room.
I would say you can go either way, depending on how much space you need and how much you have to spend.