The red screen error seems to be extremely rare (This is the first I've heard of it honestly, and looking it up other people seem to be pretty oblivious to it too) so I wouldn't worry about getting it again. The bigger problem with most units is overheating problems causing YLOD. It really is up to you what you want, personally I'd get a slim just because of how much less power it uses and the lower chance of overheating, not to mention is quieter.
Did you call Sony? I've heard they give the chance to replace your unit with a refurbed slim now.
Anyway, here is everything you need to know about safemode
http://us.playstation.com/support/an....htm?a_id=1488 but sounds like you won't be able to access it anyway.