I love heat mats and flexwatt, no doubt. I like that they are not visually obtrusive and use Flexx every time I build a rack (I have built 4 and they all worked very well...)
I actually feel safer with my heat lamps. I use standard incandescant bulbs with Home Depot dome lamps, and never go above 75 watts (lamps are rated at 150). In the winter, I use the 75 watts, but in summer I drop as low as 40 watts when the house heats up.
Even when I am SURE I have wired my Flexwatt correctly and it is on a Herpstat, I still worry about wires shorting or thermostats failing. I don't worry about that with my lamps, though it certainly IS possible.
Bottom line, we need heat, there are several options, all have their good and bad. If used correctly, the snakes should be safe.
Great points on all posts...