For those doubting this thread, I'll leave my personal experience here for all to read:
I have a moderate gaming PC (due to changing hardware, I'll just mention the power levels: 95W CPU, 150W GPU, 4 HDDs, 1 DVD drive, 2 exhaust fans). The optimal power requirements for this type of PC are in the range of 450-500W.
I had this PC equipped with a VIP 600W until very recently. It ran it decently enough, I played my games, I watched videos, surfed the internet, everything basically worked. I had a little nagging issue with one of my HDDs oddly taking a longer time to seek if remained unused for a while. I put it down to a BIOS bug and lived with it for a time.
In the course of diagnosing some other issues, I thought it would be a good idea to go in for a better PSU. So I bought an Antec. After plugging it in, I was surprised to see all the little issues gone. No more little pauses while browsing my HDD, no more odd hangs during virus scanning (I always thought that was a bug with my scanner!), and a smoother gaming experience because the GPU wasn't throttling down as much as it used to before I replaced the PSU.
Funny as hell, the Antec I bought was the VP550P, which is "only 550W" compared to the VIP "600W". Heck, when I bought the VIP, I thought that even if it's only effectively a 450W unit it should still do the job since my PC won't need more. Guess I was wrong.
For all you guys, this is the first hand experience and a benefit that was realized by a gut feeling.
Those VIP units are still fine if you're not hooking up a high end GPU or 4 HDDs (i.e. your system is strictly low-end mainstream), but if you want to put powerful hardware, you're going to want to deliver reliable power.
In retrospect, the only thought I have is that perhaps I should have gone for a Corsair or Seasonic since those are cheaper for similar wattages compared to the 4.3K I paid for the Antec VP550P, but nevertheless I got a good product.