Reply to Serato ? sounds nice

Hi guys,

I'm currently using Traktor Pro 2 with my CDJs 350 as midi controllers.
Looking around, i found that alot of professional djs are using Serato instead of Traktor.
I don't wanna start a Serato vs Traktor war, but i would like some info. I know DJTT had already made a blog on that but it's from January 25th, and Traktor Pro 2 was not out at this time so it's obsolete.

So yeah, can you give me the pros and cons of Serato over Traktor ?

Now that i gain some level, i'm likely to play at many gigs, and Traktor and it's mapping is a bit of a problem, it's not like Serato, you plug the soundcard, it's over.

Another question and it's over, what's the difference between SL1 SL2 SL3 and SL4 ? The number of decks ?
Let's say i have 3 decks, that means i have to buy SL3 ?

Really need your experience on that guys

EDIT : just so that is clear : i'm using MIDI with Traktor, but if i go for Serato, it will be with Timecode CDs.