Luis, I don't think I'll be able to the 16 GB if I get the retina so is it best to pass or worth it with 8 GB?
I still haven't seen an answer to my drive speed question between 5400rpm & 7200rpm, noticable difference? If I don't go retina I still may consider going up to next 15 for more processing power to sort of "preventobsolescence" myself. new word to combat Apples planned!
Regarding RAM: it is a tough call. If I had to buy now, I'd be somewhat divided.
The Retina display is gorgeous, and it is hard to pass up; but in sheer terms of power it is not far ahead of the non-Retina. The non-Retina can be set up with an SSD - today or a yeaar from now - and more RAM - again, today or a year from now. If you go with the Retina now, you pretty much have it as is for the rest of the machine's life (SSD upgrades are still a possibility, but likely more expensive because they are not in the standard 2.5" format; RAM upgradeability is zilch).
Regarding 5400 vs 7200: I have in the past upgraded from a 5400 to a 7200 hard drive (in my 2006 MBP), I can say that the difference in speed IS noticeable; not so much as from 7200 to an SSD (which I also did - this same 2006 MBP, that my wife uses daily, feels at times faster than my 2010 MBP, with a 7200 drive).
One other thing that I noticed when I upgraded from 5400 to 7200, and that may or may not be true in recent macs: going from 5400 to 7200 there was a significant increase in noise, both from the HD itself and because the fans got working harder. The same mac with SSD is now almost silent :-)