Downgrade to Pre-Denim - Possble?

[Windows Central Question]

Hi there I hope someone can help as I've drawn a blank on Google and various tools such as Nokia NSU/Software Recovery and NaviFirm+.

I'm currently running on my Lumia 625:
OS Version: 8.10.14219.341
Firmware Revision Number: 3058.50000.1424.0001

I'm having lots of issues with the "super sensitive touch" feature and I've tried various workarounds such as soft/hard reset/turning sensitivity to normal/high but the touch will just randomly lose sensitivity so that it's suddenly no longer possible to use fingernails/gloves etc to operate. (This was the main reason I bought this phone).

I've successfully reset the phone OS and firmware with NSU/LSRT/NaviFirm+ but none of this has made a difference. The only other thing I can think of trying is rolling back the OS to Pre-Denim as a lot of people have said that they lost touch sensitivity when they went to denim.

Would this even be possible?
If it is where would I even find a Pre-Denim Firmware/OS Image that I could apply to the phone?
Is it worth trying windows 10 to see if that offers a fix for this issue?

Just thinking of anything else I can try before sending the phone back, as it really is a great phone just doesn't properly do what I bought it for...

VMT in advance for any help.
thanks, Flick