I could see a retrospective fit as being an issue. I have the pack fitted on mine and i didn't realise till i had the car a day.
I'm not sure what tech goes into the front collison warning, I think it's a radar plus camera near the front bumper. They probably use this and maybe other stuff (is there a sensor just above the rear view mirror?) for the lane departure warning.
The rear camera might be a pain to install, all depends on the wiring.
Then there are radar sensors on the outer edges of the rear bumper for the blind spot monitoring, if a car's to the side of you and you indicate to move into that lane a beep occurs, handy, saved me once already. One thing that maybe isn't apparent is these sensors are used for when your reversing say in a car park and a car drives across you, again it beeps, very handy. Then you'd have to change the wing mirrors as the blind spot monitoring ones have a little amber led dot in them which lights up when a car overtakes you.
Imo, its more hard work than it's worth.
Just skimming through the packs I'd expect the NAV and Visibility pack to be the easiest ones to retrofit.
And one last thing, I have cruise control, has anyone with a dynamic safety pack upgraded after purchase to adaptive cruise control? I notice in pre 2017 models the dynamic safety apck was £950 and didnt include this, but now it's £1,000 and does include this, as such I'd expect it would be a straightforward addition......perhaps?