Two points I would like to make:
I'm a relative newbie but one thing i've learned is that there are space issues involved if you need/want to make "remasters" as back up copies of your system. I think i'm right in saying that a remaster can't be bigger than ~4GB but if it approaches this size then it needs this amount of free space on the / partition to remaster successfully. Correct me if i'm wrong ?. So if you run tight on space you might not be able to remaster successfully.
Also, i'm a lover of Virtualbox for testing distros and I run a full Windows XP Pro install in vbox permanently for reference purposes (I repair Win PC's). My WinXP vdi takes up 9.2GB on my /home partition and the current PCLOS2010.2Beta takes up 2.4GB.
So my message here is if you use Vbox a lot you're going to need to allow space in your /home partition.