ciao da marco

have some questions about some machines:
first, i'm not in the classical way to use samplers: sample->transfer to pc, etc...
i'm mostly in a loopy way...
so:

does the A-4000 can be used ALSO as a loopy machine???
i mean: sample different things; make songs or, better, patterns; playback syncronized to an EXTERNAL MIDI CLOCK; time strech without altering the pitch; jump from song to song / pattern to pattern...

maybe the SU-700 is better for this, but it has some bugs, and don't seems to me so much professional....the fact is that i don't wan't to buy this machine and turn it back 2 month after because of boring limitations...

the final alternative: a PC based loopy way of sampling and playing patterns: Acid Pro V2 (Sonic Foundry)...
but, again:
is this combination stable, or will have terrible problems using a PC as a groovebox synced to external machines???
this combination (machines + PC as slave to midi clock) will be solid in time???

thanx

marco