They're actually hard to compare, being each is a totally different scenario. PSN outage affects all owners but - relative to RROD - is very short term. RROD affected smaller groups of customers at a time over a very long period.
RROD was purely self created issue, a result IMHO of MS rushing the 360 to market instead of taking longer and producing a better piece of electronics.
PSN is a purely external issue (FYI I don't hold with all the "asking for it" crap. Hacking anything is a choice) and no down to Sony directly themselves.
If I had to try and generalize then RROD was perhaps worse in that - probably - it cost MS more than PSN will cost Sony, it was self generated and therefore less tolerable from the company itself from a consumer perspective.
Looking at PS3/360 sales I don't think (unless PSN remains down for months) I'm not convinced either RROD or PSN will have hugely affected demand for the consoles themselves that much.
Try to be reasonable... its easier than you think...
