The Pro-2000 and Pro-4000 are definitely cross-compatible. The 1000 should be very, very close - it's actually the exact same head from the 1000 all the way up to the 6000. The only thing that gives me any pause at all is that the ink delivery to the head is unique in the 1000 (coming out of the head, which is what really matters, it should be the same - but I'm not sure the 1000 is identical before that point). They may well be compatible, and if not, they're really close...