jamesh wrote:If you have a PC nearby, try powering the Pi off that (with a decent cable) - that certainly helped mines stability. I had a .85A Kindle charger that was right on the edge when stuff was plugged in, and a 1A Chinese PoS that wouldn't even boot. Quality does seem to count.
You are contradicting the official Quick Start document here ("Do not attempt to power your Raspberry Pi by plugging it into a computer"). And Gert ("Danger is that initially it seems to work", but "plainly connected in a way it should not be").
But I have also found my Pi to be both perfectly stable and in spec when powered from either of two different computers. And also when powered from the USB of either of two different TVs. Including with heavy network traffic and HD video. I wonder how the success rate of random micro-USB chargers really compares.
As you say, a good cable with low resistance power wires is important. Also, the rear sockets are likely to have less voltage drop because they are soldered onto the motherboard instead of using an extra cable inside the case.