I'd say putting a diesel in it would be a ballsy move by Robinson considering there are hardly very many airbourne in aeroplanes now.... I reckon Robinson will release a turbine version first and spend a lot longer trying to get a reliable diesel sorted, I think they have learnt from the past and will be very reluctant to move away from an airframe design/shape that they know works............. By god those 44s are ugly! but they are nice to fly, I know I'd rather have an ugly machine that handles well than a hottie that flys like a pig.
A flat floor wouldn't go astray either.... with perhaps removable rear seats like a squirrel maybe?