The SD1m is a banding machine, really. It need a lot of PP to render it good. The DP3m is far better at all levels for this focal.
The SD1m do not have any kind of live view. You might think "...ok" but no. A DLSR, especially a foveon DSLR, need live view.
The next SD might have it. If not, it will be just ridiculous.
So if the next SD come the last, after the DP3Q, it might be a very good Quattro gear.