[One (M8) Q&A, Help & Troubleshooting] Alvinator9000:
Roundabout Method

I don't mean to be a grave digger, but this method worked for me, perhaps someone else may find it useful:

Problems:

I couldn't get access to the partitions through adb shell, it kept giving 'access denied' and adb was not asking SuperSu for root permissions.

Solution: [I disclaim everything for legal purposes]

After a number of things, I finally copied the following into Google Keep (you can use anything, notepad, whatever, mainly to transfer a script-like function). WARNING, you DO need an External SD CARD (Verify through Root Explorer that the /sdcard2/ is your EXTERNAL SD card. Make a folder on it called "World" [or whatever], it will save there, else change [use replace all in notepad?] it to work):

dd if=/dev/block/mmcblk0p1 of=/sdcard2/World/mmcblk0p1
dd if=/dev/block/mmcblk0p2 of=/sdcard2/World/mmcblk0p2
dd if=/dev/block/mmcblk0p3 of=/sdcard2/World/mmcblk0p3
dd if=/dev/block/mmcblk0p4 of=/sdcard2/World/mmcblk0p4
dd if=/dev/block/mmcblk0p5 of=/sdcard2/World/mmcblk0p5
dd if=/dev/block/mmcblk0p6 of=/sdcard2/World/mmcblk0p6
dd if=/dev/block/mmcblk0p7 of=/sdcard2/World/mmcblk0p7
dd if=/dev/block/mmcblk0p8 of=/sdcard2/World/mmcblk0p8
dd if=/dev/block/mmcblk0p9 of=/sdcard2/World/mmcblk0p9
dd if=/dev/block/mmcblk0p10 of=/sdcard2/World/mmcblk0p10
dd if=/dev/block/mmcblk0p11 of=/sdcard2/World/mmcblk0p11
dd if=/dev/block/mmcblk0p12 of=/sdcard2/World/mmcblk0p12
dd if=/dev/block/mmcblk0p13 of=/sdcard2/World/mmcblk0p13
dd if=/dev/block/mmcblk0p14 of=/sdcard2/World/mmcblk0p14
dd if=/dev/block/mmcblk0p15 of=/sdcard2/World/mmcblk0p15
dd if=/dev/block/mmcblk0p16 of=/sdcard2/World/mmcblk0p16
dd if=/dev/block/mmcblk0p17 of=/sdcard2/World/mmcblk0p17
dd if=/dev/block/mmcblk0p18 of=/sdcard2/World/mmcblk0p18
dd if=/dev/block/mmcblk0p19 of=/sdcard2/World/mmcblk0p19
dd if=/dev/block/mmcblk0p20 of=/sdcard2/World/mmcblk0p20
dd if=/dev/block/mmcblk0p21 of=/sdcard2/World/mmcblk0p21
dd if=/dev/block/mmcblk0p22 of=/sdcard2/World/mmcblk0p22
dd if=/dev/block/mmcblk0p23 of=/sdcard2/World/mmcblk0p23
dd if=/dev/block/mmcblk0p24 of=/sdcard2/World/mmcblk0p24
dd if=/dev/block/mmcblk0p25 of=/sdcard2/World/mmcblk0p25
dd if=/dev/block/mmcblk0p26 of=/sdcard2/World/mmcblk0p26
dd if=/dev/block/mmcblk0p27 of=/sdcard2/World/mmcblk0p27
dd if=/dev/block/mmcblk0p28 of=/sdcard2/World/mmcblk0p28
dd if=/dev/block/mmcblk0p29 of=/sdcard2/World/mmcblk0p29
dd if=/dev/block/mmcblk0p30 of=/sdcard2/World/mmcblk0p30
dd if=/dev/block/mmcblk0p31 of=/sdcard2/World/mmcblk0p31
dd if=/dev/block/mmcblk0p32 of=/sdcard2/World/mmcblk0p32
dd if=/dev/block/mmcblk0p33 of=/sdcard2/World/mmcblk0p33
dd if=/dev/block/mmcblk0p34 of=/sdcard2/World/mmcblk0p34
dd if=/dev/block/mmcblk0p35 of=/sdcard2/World/mmcblk0p35
dd if=/dev/block/mmcblk0p36 of=/sdcard2/World/mmcblk0p36
dd if=/dev/block/mmcblk0p37 of=/sdcard2/World/mmcblk0p37
dd if=/dev/block/mmcblk0p38 of=/sdcard2/World/mmcblk0p38
dd if=/dev/block/mmcblk0p39 of=/sdcard2/World/mmcblk0p39
dd if=/dev/block/mmcblk0p40 of=/sdcard2/World/mmcblk0p40
dd if=/dev/block/mmcblk0p41 of=/sdcard2/World/mmcblk0p41
dd if=/dev/block/mmcblk0p42 of=/sdcard2/World/mmcblk0p42
dd if=/dev/block/mmcblk0p43 of=/sdcard2/World/mmcblk0p43
dd if=/dev/block/mmcblk0p44 of=/sdcard2/World/mmcblk0p44
dd if=/dev/block/mmcblk0p45 of=/sdcard2/World/mmcblk0p45
dd if=/dev/block/mmcblk0p46 of=/sdcard2/World/mmcblk0p46

(Copy with or add a final return character for the last line to run okay)

I installed Terminal Editor

I went into Terminal Editor, typed "SU" pressed enter, a window pops up from SuperSu, Grant TE superpowers!!

Now, copy the above 'script', paste into TE (It will start immediately)

Connect your phone to your computer, and copy the World folder from your external storage to your computer.

PS it takes about 3GB on near-stock, without User Data.

Mainly I wanted the radio files and such, but whatever now I have a whole backup :)