Barney kindly provided this addendum to where I left off:
“In this post you pose a great question: the file sizes are much larger, but what price image quality?
Maybe you can inform viewers about this subject please?
Storage cost per RAW image file of 35MB from a full frame 36Mpx camera is 0.3c
The price is extremely low! So low it is not worth your time to go through your folders to clear space.
WD Black 4TB drive with a 5yr warranty costs $309 now (as at July 2015)
A 36Mpx image from Sony A7R has size: 35MB RAW, or 24MB Jpeg
Folder size is 6.13GB for 179 RAW files therefore an average RAW file size of ~35MB is OK to assume
A 4TB HDD has 3.72 TB of available space after formatting (~93%)
3.72 TB/ 35MB = 106285 files of 35MB
Storage cost per RAW image file of 35MB is 0.3c
Also – Seagate now (as at July 2015) produce a $399 8TB HDD for archiving http://www.scorptec.com.au/product/Hard_Drives_&SSDs/HDD-_3.5%22_Drives/58205-ST8000AS0002
Editor's note – not that I've had much success with Seagate HDDs… caveat emptor
1 July 2015 – post added
2 July 2015 – edits