@huima More RAM means more heat and electricity use, bad when computer is in living space. Yes, virtual machines are good. Do you also have a tablet with Android or netbook with Ubuntu in parallel?
These days you can get huge amounts of memory to your computer for peanuts. I just updated my iMac ( late 2009 model ) to use the full 16 gigabytes of memory possible to use on this Intel i5 machine.
Being able to run virtual machines, large heaps and numerous different programs at the same time is a huge productivity boost – and these days 8 gigabytes already proved to be too little. With the 16 gigs I should be able to continue enjoy and be productive on this iMac for years to come. And the cost was just a little over hundred euros.