I have a lot of Gibraltar on my rack. I also have some Pearl clamps on my down tubes. Personally, it is cheaper for me to get Gibraltar hardware locally than Pearl. From the Pearl equipment I have used, they really seem about the same. Keep in mind, these are the only pearl thing I have. http://www.guitarcenter.com/Pearl-AX...13-i1140412.gc
I got them because I found a deal on Ebay where I got 4 clamps for 50 bucks. Compare that price to this: http://www.guitarcenter.com/Gibralta...31-i1139070.gc
When you are building a rack, that price difference adds up.