unfortunately I dont have an exact number. Not my job to count. However, the scoop is that one of apple's suppliers shipped a rather large, bad batch of capacitors that were used in power supplies and logic boards. Hence the REA status for certain machines. So, we've repaired a decent number. But thats consistent with any REA issue. A bad component makes it into manufacturing, and instead of the component supplier getting the rap, apple fixes the issue, and takes the heat.
Way I see it, its no different than the power supply replacements for Mirror Door G4's, the iBook logic board program, etc. Interestingly enough, the iMac G5 in my house, no failures whatsoever. Its perfectly solid
Last thought. Almost every customer that brings in a machine asks us "If we've repaired a lot of these." Or, they ask us, "Do you see a lot of this type of problem?" I always tell them that I'm the wrong person to ask, since the only machines I see are the broken ones.
If it'll put it in perspective, we replace a lot more hard drives across the spectrum of machines than we do specific parts in any one machine. Hard drives absolutely fail the most. All types and brands. We've even seen them catch fire. And by that I mean burst into flames. Buy your applecare, back up your data. Your applecare will cover your hard drive in warranty. out of warranty, buy something with a good warranty (3 years or better) While I cant promise that the logic board in your Blue & White will ever fail. I can promise you that one day you WILL loose a hard drive.