Thanks for showing interest, maybe I didn’t explain clearly, the idea of the script is to create a backup image which is only the size (slightly bigger) of the used space of the installation, making it very simple to move installations to smaller memory cards, and also saves a lot of time when writing the image to cards.
Rather than writing a 16/32 GB image, its now just writing 3/4GB as thats all the space that was used.
More importantly, once i’d ruled out power as a cause, I’ve tracked down the issue and its a faulty USB stick thats causing it, I swapped the USB sticks from each pi and rewrote the images, and the problem follows the USB stick, now its the PI2 on Raspbian that has the very slow write speeds, and the OSMC Pi3 is performing exactly as it should.
Its something I stupidly overlooked at first as both sticks were brand new, identical, and taken out of the packaging at the same time.
I’ll be returning the faulty stick for a replacement as its less than a week old.
Mark this one as solved!