I wonder what the efficiency is at higher temperature differences.

For example, I would like a water-sourced aircon which cooled a radiant or chiller circulating system on the cold side, while heating incoming water for hot water on the hot side (plus an 'overflow' cooling ground loop if necessary). Maybe this isn't beyond the ability of current systems, but I think having a fairly large gap of 60C hot/5-15C cold is inefficient currently, and maybe a reason you don't see this obvious setup too often.