Jeff - thank you. Your excellent comments prompted me to go back and relearn some compressor fundamentals.
Attached is short paper that I "thought" I had saved and I did. It goes over the scroll compressor history and briefly the construction. The comparisons of different compressor are listed and contrasted - but not rolling piston types. It is a quick read and I found it helpful.
Is there a similar paper on rolling piston types out there?
http://dms.hvacpartners.com/docs/100.../811-20065.pdf
Steve