... I now know more about thermodynamics than I ever wanted to know... and I still don't know very much lol. I'm also reminded of why I changed majors in college from engineering to CS.
anywho... things to consider in this debate:
This is a pendant, is the bottom of the pendant enclosed? therefore making this a sealed unit to direct airflow? (if not, you may wish to consider it, it will help with keeping the tank cool)
The vents are located top and center of the hood, however, there will likely be a reflector of some sort located above the lights and, therefore, between the light bulbs and the vents themselves.
can you give us a little more info on the placement of the bulbs and reflectors in your hood JackDP and if the you plan on putting a glass/plastic bottom on the pendant?