Intel has put its Matrix Storage driver, official production version 7.5.0.1017, online. Among other improvements, it is supposed to fix iTunes/QuickTime problems for good. I have to say: finally - it was about time! Hopefully this ends months long saga of destroyed RAID drives. I guess we'll soon find it out if the problem is fixed. As a precaution I'll make a copy of my disk content using excellent Acronis True Image software right before installing this driver and later iTunes. Just in case. May the force be with the brave.
Go get it here.
UPDATE: I've been running the above RAID driver and iTunes 7.2 for a couple of days now and there are no problems. Not sure about the disk speed when using iTunes though.