i use the 404 for performance cuz its such a rugged beast. but while i'm only just getting used to it, i think my fave SP is the 505.
the comment ^^ above about it being an mpc-lite is pretty accurate in all honesty....but i also have a mpc1K and VASTLY prefer the workflow and speed of the 505 to the 1K.
little things like a single-button press and easier naming / filing directories are the difference between being creative and being super careful to not overwrite yr stuff. also, fx selection and manipulation with knobs is far preferable. with the 1K i always feel like i'm doing defrags on a server or something.
my two requests for ALL SPs IN THE FUTURE are 'pitch' and 'pan' as knob-turnable options.
also: a free SP for every 3 purchased.

