8GB is plenty and then some. im just a very very busy person. I could probably do everythng on 8gb, but VM's take up a sizeable portion. if you want them to work at decent speeds, they need 2GB each, and they just take all of it at once. I also have a vertex3 ssd which has a read rate of about 400mb/sec.
My PC is my work station. It makes me money. I can't afford to sit there waiting while something compiles, or close things to open others.. Its just like any other profession. Mechanics have their tools... My tool is my PC. If i want to be the best, i need the best.