i have only used powersun once, and would not buy it again for my chameleons. First off, they are exspensive, around $50 a bulb. Now I don't know about you, but 50 bucks for a light bulb is a little high. Also, they have to be replaced every 6 months to keep the proper UVB UVA levels emitting from the bulb. Not to mention the horror if you ever droped the light by accident. My little brother knocked mine off and broke the bulb, I had just bought it too... 
Even though you don't want to, I would suggest getting a florecent tube to do the job. They are much cheaper, around $15, and you have a slim chance of breaking them. You also have to replace them, but 15 buck a bulb is better than 50. LLLReptile.com has some good inexspensive "tubes" that are great to use.
But as for the over heating issue, the powersun does give off a lot of heat. I would reccomend it if you were going to use it on a monitor of some kind, but not a veiled.
I would just buy a florescent fixture and the bulb(llreptile.com), then get a dome light and a regular bulb for you veiled to bask in for heat. Depending on how far away it is from the light sorce determines the wattage. A 60 watt is a good choice, but to make sure, place you hand where you cham would be under the light and hold it ther for 5 min, if you hand starts to burn, its TO hot, so move the light further away from the spot. around 90 deg F. should be the temp oh the "hot" spot. You can place the florcent light across the area you cham spends the most time on, that ensures it will get the UVB UVA rays.
Hope this helps
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Kaitlyn
0.1.0 Jackson Chameleon (Kokoro)
0.1.0 Veiled Chameleon (Eclipse)
0.1.0 Leopard Gecko (Sway)
1.0.0 Ball Python (Mitch)