Hi guys,
my first post here.
I was wondering if there is a comparison chart between the 303 and the 404.
or maybe some of you guys can list the key differences?
What will I be giving up by choosing the 303 over the 404...
I read somewhere that the 404 have a mark button for chopping samples - how exactly does this work? and does the 303 have this as well?

check this thread for the 303 / 404 thing:

viewtopic.php?p=4457&highlight=#4457

i belive they both have a mark button. you play a sample, then when you get to the part you want it to start at you hit [mark]. then when you get to the part you want it to end at you hit [mark] again. then you can make fine adjustments with the [start/end/level] button and the knobs. it's a really fast, intuitive way to do your chops and i feel it improves your ear, instead of visually chopping waveforms, which seems more cerebral and less intuitive.

the 404 can only resample 2 pads at a time. if you try to do more one of the others will shut off. you can get around this by layers of resampling, but
there is audio degradation every time you resample, though usually not a ton. i THINK the 303 may let you resample more pads at once, but i'm not sure. i'd get the 404 anyway, for the reasons outlined in the above link.

i think it improves your timing too