eyecandi Leds do put out as much heat and the reason you probably have less temps than your 600w hps is because your led is only 400w. You could have just switched to a 400w hps and would have reduced heat.. and had a higher yeild.
The whole thing about LEDs reducing heat isn't true if you replace 600w of hid with 600w of led overall heat is going to be about the same. Its just spread out more with the led. Also you need more watts of led light to replace HID from what I have seen I have seen people pull 1.3 gpw with 600w...