If you can get a deal on the SA7001 KI go for it. Be aware though that if your existing kit is bass-light or lean, this won't add any of that to it. Fantastic midband, very nice rounded treble; one of the best CD players I've owned. The bass is articulate - both SACD and CD are excellent on it. Works well with whatever you care to play on it too; we've got a wide range of CDs and there isn't a bad one yet.
Word of caution though, if a CD is badly recorded, it'll show it up in an instant. This player isn't forgiving in the way some Linn gear can be. That's a good thing IMO, but it might not be for everyone.
EDIT: You also listed the SA7003, this is the replacement for the SA7001, the SA8003 is the replacement for the SA7001-KI. Marantz have dispensed with this long-standing designation for KI graded equipment.