If you are locked into 120 film because of the Coolscan, then you may want a dedicated 6x9 camera. However, a 4x5 system is often cheaper with no to little weight gain, and you have the option of shooting different formats - 6x12, 6x9, 6x7, etc. If you are comfortable with the image quality you get from your Super 23 using the groundglass to focus, compose and add movements, then you will be comfortable with a 6x9 camera (though films backs should be considered - I believe the Mamiya backs are the best).

A digital back complicates this considerably due to the precision required. If you go with film only, then you have a lot of options at a lot of price points. If you are set on digital, then you need a very precise camera, and the options dwindle to only a few, with the best costing beaucoup $$$, and weighing a ton due to the geared movements.

IMHO the Linhof baby technika is a sweet camera because it is so versatile. But amazing work can be done with a Speed or Crown Graphic.