@kshi No the multiple keystroke issue hasn’t just started it started when I switched versions to the Matrix Nightly build. As the MX3 works out of the box I did nothing with it until the repeats got annoying.
First time I ran ir-keytable on the device I did notice that the -P parameter was missing though once I ran the ir-keytable -D 500 -P 125 command it seems to be persistent on reboot and working fine, so I am leaning towards either a config file that got borked on a nightly upgrade or I will just never know.
Very aware of the MX3’s propensity to “eat” batteries, its part of the reasoning I decided to invest in a decent Youshiko battery charger and start the move towards switching to all rechargeable batteries to be more environmentally friendly. 
@Betatester Not that smart, I just guessed a starting point that worked.