EDIT: For some shots, I do need to be further away and then crop around the main object
Does that change anything?
You're going to lose resolution, so your cropped images will have far fewer pixels.
Also, keep in mind that Aperture and some other software will not process SRAW.
Your best bet since you will crop some shots is to shoot in full-RAW. Once you process then convert it to an 80% or so JPEG and delete the RAW if the photos are for one time use.
I may even shoot JPEG+RAW in your circumstance for a while, and see how often you even need the RAW if you are short on HD space.