Hi there,
if all you do is art reproduction, my view is that a scanning back is probably the best option:
- cheeper,
- higher resolution/better image quality,
- better color reproduction thanks to the fact that there is Bayer interpolation,
- larger surface covered makes it possible to use regular LF lenses (no need to buy the new smaller image circle Digitar like lenses),
Betterlight is a key contender if portability is required, if it is not, you have other options (Phase + a German manufactuer whose name I have forgotten).
I guess that it all depends on the kind of art work you are trying to reproduce though...
What I mean is that at the resolution of a BL 6K (8000x6000), it seems that the diffraction limit is around f16 on LF. If you go higher in resolution (Super 6K or super 8K), you will need to open up you lenses even more if you want to tap into the resolution provided by the back.
This is OK if your art work is more or less flat. If it is a 3D sculpture that you need to be fully in focus, then there is probably not too much sense in going for the super high resolutions, unless you are willing to to DoF stacking...
I haven't done much art reproduction, I'll let more experienced contributors comment further.
cheers,
Bernard