Here are some helpful articles on the subject.....
Radiant Barriers: A Solution in Search of a Problem | GreenBuildingAdvisor.com
Radiant Barriers | My Florida Home Energy
FSEC-EN-15
Articles about Radiant Barriers - tribunedigital-orlandosentinel
Radiant barrier insulation may not recoup cost
So...the bottom line...is it worth it?
That is a multifaceted complex question. There are different types of radiant barriers. The fact is that they can save some energy cost. The better question is, can you recoup the cost?...especially in a new home with an R-30 insulation?
Would you be better served by installing more insulation instead perhaps up to an R-38?
Does it keep your attic cooler? Yes. As a person who crawls/walks in about 400 Villages attics every year, I do find that the attic is cooler. Is it worth the cost? What is the payback? At the risk of sounding rude, (and I am not a rude person at all), if you are 98 years old, it is pretty safe to say you will not recoup the cost. How long will you have your home? Would this upgrade be perceived as an enhancement when selling?
I have seen some radiant barriers not installed well and starting to fall. I have seen some installs that were awesome.
It is not an easy yes or no question. I'm sure this will not be the last word on the subject.
Frank