DISCLAIMER: The following is all IME, IMO, YMMV, yada, yada, etc. Take it as you will...
There are a couple sayings that I live by that normally... (A) Mix with your ears, not your eyes - (B) Some gear does things with "more style" than other gear.
Here's a prime VISUAL example of (B) which relates to (A) and leads to (C) below...
http://www.massivemastering.com/special/loudness.jpg
The top is the untouched mix file - Healthily and happily undistorted, with excellent dynamics and a wonderful "smooth" and "warm" quality to it, sitting around -19dBRMS
The second file was mastered through a fairly schveet analog chain into excellent quality A-to-D converters. It sits in the mid -11dBRMS area and "appears" to still retain a good amount of dynamics (which it does) and a certain "smooth" and "warm" quality (which it also does).
The bottom version is the same file, through the same chain except for the limiting - which was accomplished through my personal favorite digital limiter, the UAD Precision Limiter. It sits a little lower in volume in the low area of -12dBRMS and "appears" to be essentially clipped with less dynamics (which is true) and a certain "cold" and "harsh" quality, mostly in the highs and upper mids (also true).
As good as the UAD limiter is (again, my personal favorite digital limter), the difference in appearance - AND sound - is pretty striking. And this is just one link in the chain - The one that arguably has the *least* effect on the overall sound.
Again, take it as you will. It doesn't take much to beat the crap out of a mix.
Hence my other saying - (C) When it counts, use the right tools. If you don't have them or don't know how to use them, find someone who does. And of course (D) If it doesn't count, and you don't care, do whatever the hell you want - Just don't be pissed off when nobody else cares either.