A-V receiver power ratings

I feel it's important to remind the forum (as a refresher) that many power ratings of A-V receivers can be deceiving. When an A-V receiver states for example that it can produce 100 watts x 7, it doesn't necessarily mean it can deliver 100 watts to all 7 channels simultaneously. It must state "All Channels Driven" into 8 ohms or the like. If it doesn't, then it means that 100 watts can be delivered to the two main channels but when the receiver is in either 5.1, 6.1, or 7.1 mode, the power delivered is reduced. Marantz for example guarantees a min of 70% of its rated power when in surround sound mode. They claim this 70% is conservative though. They don't print that anywhere but my Hi-Fi store sales person explained this to me recently. NAD gives a "simultaneous power output" rating. So just something to be aware of if you're basing an A-V receiver purchase decision on power output in surround sound. Discussion is welcomed !!