Best help for confidence in the cockpit is training and experience.
I haven't used any stability augmentation system so can't comment on what that system will do for you.
The whistles & bells I have added are:
Aircon - and I love it!!!
Emergency floats
Radar altimeter
Flymap L with synthetic vision
I was forced to add an ELT by regulations, but always preferred the PLB approach.
I tried to join the ADSB trial, but I would need to change the panel-mounted Garmin and cost became a factor.