I do not know the relative power requirements for the ND compared to the Delco....
However, since both are rotaries I suspect that difference is almost zero...
I think the differences when choosing between the two may come from things like the ND being easier to fit along side an engine compared to the (BIG) pancake design of the Delco....and maybe the ND has a crankcase to store oil...... and potentially in reliability... particularly in the rebuilding of them.....
I think the fault line in compressors is between the york type... which is basically an inline two cylinder engine... with the accompanying problems with mass changing directions... vibration...the rotaries chop that up into lots of small compressions in little movements...