The KK is respectfully deep, but in typical Korg fashion it has too many parameters to program. It also has an unnatural "sheen" which to my ears doesn't sound anything like the filters it's supposed to be emulating. The frequency nodes where the phase shifts occur in a sweep just seem wrong when compared with the real deal.
The A1 is much more limited but it's so much easier to program. Plus dissecting a patch to learn why it sounds good is very straightforward without having to go on a safari. And the analog emulation sounds better, although resonance doesn't scream as much as true analog.
If you have the Blofeld, I'd skip the Sledge. You have the same engine and more waveforms. I don't see enough of a differentiation to justify it.
