All LS lenses are modyfied old Mamiya AF lenses accept new zoom lens and maybe the 110 mm. So thay all have the same classic lensdesign based on classic german lenses ( distagon, planar, sonnar). The improvements are made in higher production standarts and newer (better contrast) coatings.the Schneider-like lenses are still mamiya lenses with Schneider LS shutters and supposed german coated glasses. Ofcourse the newer lenses will be sharper at larger apertures but not at optimal working apertures, mostly app 11. the 55 is a still a not problematic lens design, so even older lenses will perform well with digital backs. The problem will apear with wider lenses.
to the 150 mm lenses: there are 4: the older AF 3,5/150 mm (based on older 645 non AF), the superior A verion 2,8/150 mm that was redesign as IF D version (closer focusing distance) and the 3,5/150 mm LS that is simply improved older 3,5/150 mm ( much better wide open). I think the biggest problem at developing better lens design at middle format for digital use will be the price: an Otus made for 645 format would be too big and too expensive. lenses like Rodenstock HR made for 645 AF cameras ( lens +focusing system, aperture, shutter, AF system) would also get ridiculos prices.