I went with the 800w's because I just wanted more surface area covered by the lights. Also I was a bit worried about the design of the lights, that's 3 400 watt ballast all running to a single 14g( I think) wire plug in. I felt one that was running for a while and it was pretty darn warm. I don't know if your math is off but, my room is sealed and the 18,000btu ac will bring the temp down to 76deg if I want, I run it at 82-85 with co2 at 1500ppm. I also have 2 dehumidifiers running which make a lot off heat and the c02 burner although its water cooled.
The plants look good. I went back and double checked my math on the temps which led me to go back to their specs to see what the recommended area coverages are for their products and how many lights/lamps it takes to provide that coverage. Here's what I found:
The Parlux spec for the single 400 watt light is 47.2" (L) x 11.8" (W) estimated to cover a 25 sq ft area and a VEL or Pupil reading *92,883 which would be like a lumen output of the lamp.
The Parlux spec for the 800 watt light which consists of two 400 watt tubes sharing the same housing is 47.2" (L) x 22" (W) with a VEL reading of 185,776 (double that of the single 400) and will cover a 50 sq ft area. For the single 800 watt light to cover a 50 sq ft area you would have to raise the light since lamp orientation has not been adjusted or canted to throw light over the claimed 50 sq ft area.
To raise the lamp for coverage you lose intensity at the canopy. I noticed by your fixture layout you kept the 800 at the same height as your 400's and you did not adjust the spacing to take advantage of the 'wider area coverage', which tells me you're just running putting more heat into the room with greater intensities under the 800 than you would have under the 400's. So unless you're getting double the flowering sites and yield under the 800 I don't see why you wouldn't just be better off with their single 400 lamp.
* The problem with this VEL value is that on the next page they have a chart where they show VEL (Visually Effective Lumens and Pupil Lumens are the same thing as a measurement of a lamps intensity) they show as a Pupil Lumen per Watt that is listed as 150 PL/W (fourth line down on the top chart). So if you take their 150 Pl/W (which isn't relevant to plant light anyway) and carry it out with the wattage of a 400 watt lamp (150 x 400 = 60,000 VEL) you are way off the 92,883 VEL as stated on the spec sheet. On the 800 watt light the order of magnitude is increased in that the 150 x 800 = 120,000 VEL not the 185,776 VEL as shown in the specification.
Both of these intensity values can't be right. One has got to be wrong and that will definitely have an impact on temps by the number of lights/lamps for the recommended area coverage
