I have both SD1000 and V3.

The SD1000 sounds to me more versatile to play GM-files out of the box. Whereas the V3 has far better sounds to play solo.
Just my opinion.

Also, the SD1000 (like all Ketron-products be it SD2, SD4,SD1000) produce much more background-noise, as a result of using cheap DA-convertors in these little boxes.
The V3-module produce nearly no noise…

For me, the V3 is the better choice in Sound-Quality, and Sound-Kwantity!

Best Regards,
Carlo