If a fluorescent bulb, for example, is 200W, and is 15,000 lumens, its lumens per watt (LPW) is 75: 15000/200 = 75. You want this number as close to 100 as possible, although some lights like Sun God's Mini Lotus can go higher than 100.
Bulbs with a LPW of 50 will still work, and many work very well, but there is a lot of wasted energy there (bulbs like this suck up the same power as the bulb next to it but just don't output as much light). I try to stick with bulbs that are ~70+ LPW.
At any rate, this is why the "wattage equivalent" isn't useful - it doesn't really tell us anything relating to bulb effectiveness.
Lumens, Color temp, and wattage are the three main items needed.
Heat temperature has a ton of variables such as room's ambient temp, how tight the enclosure is, whether there's a fan, etc. I generally start at 12 inches with higher-intensity bulbs (fluorescent, not 400W HPS or anything) and work my way in. If it's close enough that you can really feel the heat on the soil surface, it's probably too close.
Since you're in research mode, here are a couple threads that you may find useful:
http://www.flytrapcare.com/phpBB3/lumen ... ml#p144568
http://www.flytrapcare.com/phpBB3/best- ... ml#p153234