The perceived scanline issues with the PSP 3000 aren't unfounded, but I honestly and truly don't notice the phenomenon 99.9999% of the time. For me, the tradeoff of having a brighter, more vibrant screen (which you can revert to the original, non-vibrant mode in the screen options) outweighs the few times I see a scanline blotch. I haven't played the PSP-2000 in a while, but I've read that the light ghosting present on that screen isn't as apparent on the PSP-3000.
Still, either way, the 2k and 3k PSP systems are both great form factors, and the sales going on right now at EB/GS make it a nice buy. I recommend the steal of the month at the EB/GS Game Days sale which is a $4.99 new copy of the UMD movie "Stealth." The movie was wack, but it comes with a free copy of Wipeout Pure! Previous system pack-in Daxter is $4.99 used at GS/EB, and well worth picking up, too.