ok,
i finally bought back an mpc 1000 (with jjos2xl, hdd and max ram, waiting for the fatpads, now it has new padsensor and cool black normal mpcstuff pads, which are pretty bad after being used to the good mpc live pads...)
i can't do anything but confirm what my impressions were from memory now that i can compare the mpc1000 to the mpclive mk1 realtime in the flesh.
as i remembered, it has nothing to do with "grit" or lofi or nasty sound. the sound of the 1000 (and of course the 2500) is crystal clear, pristine, very similar to the current mpc line. where it differs is its strength, its punchyness, even with some very dull drum samples i hear better dynamics and better overall sound coming out of the 1000, especially when different sounds are mixed internally. as i recalled, the filters are really nothing to write home about, but they do their job, and with jjos2xl great q-link control they are very fun to use.
the sequencer, oh boy, even if it's old it is such a joy to play with, time signature freely and easily changeable PER BAR, step recording, the overall feeling of being home

i think jjos2xl is my favourite sequencer EVER (and i tried many, hardware and software).
of course, everything regarding browsing and managing is tedious compared to touchscreen goodness, file loading and saving, renaming etc... sample editing tho... i was afraid of being too spoiled by the gorgeous touch screen but overall is a very cool experience, chopping too...
anyway, this said....
the weekend before getting my new 1000 i performed a liveset on a mid sized but very punchy P.A. and the mpc live performed very well, the sound is more than good, clear and punchy and huge, so, there's absolutely no "need" to go back, but the 1000 is on another level. not necessary, but if you are like me, obsessed by the magical psychophisiological properties of a proper kick\snare\hat\bass groove that kicks you in the balls on a dancefloor than i suggest to check it for yourself. the dynamics are simply something else, requiring ZERO effort to spit out a GREAT sound!
p.s.: another quick comparison i've done is: mpc live mk1 vs sp404mk2 vs mpc 1000.
verdict is: sp404mk2 a bit more powerful than mpc live , but mpc 1000 eats them both alive. now what is worriyng me a bit is that i'm afraid of running the 1000 outs into the sp for live fx... tried it and it definitely sounds weaker thru the sp, while the live definitely sounds stronger thru the sp...
one solution is to use an aux send on the mixer to send a copy of the 1000 signal to the sp and then using faders to "xfade" between original and effected (of course you need a pre-fader aux send to do it properly)... but i think i'll end up not using the sp...