Ive not compared them tbh, but if you render without maya being open (either right clicking or comand line rendering) it does speed up the render time quite a bit, also lowering the RAM requirement will let you squeeze out every last bit that your syetem can muster for say, paint FX hair, or any other RAM intensive task at rendertime, that might otherwise cause a crash.

For example if I try to render with SSS some 2048 maps for a character, hair generated using paint FX and a hair system with maya open i'll crash right off the bat as it maxes it out the RAM. If I cache the textures and then render form the cmd line or right click with no other programmes open it will render it out, which is a good thing! Other than that I would probably just render in passes the lower the system demand (do the character sepperate and then a hair pass over the top, which gives grater control over the look in compositing)