All you wrote is true.
To be exact.
Idyn, D-lighting are a split tool.
The toning aka highkey lowkey adjustments to stretch DR, in practise a smartlighting action are jpeg only effecting.
The modes which stepping down initial lightmeatering is effecting exposure of the sensor thus the raw file.
On or off?
My personal use is based on my normal shooting envelope.
I walk with my family around and take shotscof things i think would be nice to turn in a image. No tripod, nor minuts of preperation. Only a quick choice how to get my thought in the camera.
I have idyn on Auto. So it only activate in 1/3 2/3 3/3 -ev if it detects a overrun in DR of the scene. In my older camera , micro sensor, i alway shot -1/2ev compensation as default knowning underexposure is more easy to recover then overexposure.
Now i have both worlds, normal exposure and a automated correction if scene needs it.
Less time needed to click snapshot…
less moawning family members waiting for me.
In my memory, i tested it long a go, my manual EV correction overrules idyn.
The weather here is dull no High Dynamic scene so i can’t test this right now.
Further i have 4 custom settings.
1 1.4x electronic zoom, jpeg only, for the moments the lens is to short and i need cropped light meatering.
2 bird mode, back focusing and locking and tracking mode or centrebox mode.
3 a bare Aperture mode, all aid systems off. I am in control.
4 geesh down know.( i know again a copy of Aperture mode best settings…)
(sign to re build my customs to my new use preference… 
)
Extra is when i meshed up settings in A or P i just turn to customs and see what that has set. Then i know what i decided after closly reading the theory behind the setting. Best option so to speak.
If any reader here have a idyn or active d-lighing on there camera and is in summer, high dynamic scene in garden, please test automode and manual override by spotmeatering and ev compensation. (i am fairly sure its overriding idyn’s settings but not for sure.)
I your case or anyone who are mostly take photographs not snapshots and P&S, indeed turn everything “magic” and automated aid of.
All is slow shutter compensation, shotnoise compensation, a aid which i think if i am remembering correct ( we posted about this here) also for rawfiles a good feature.
Lensshadow correction, vignetting, is jpeg only but straingly enough dxopl seems to read and applies this when i activate it in my panasonic. And thus overshoots this correction because it has the same in optical module… Knowing this i don’t turned it of but in certain shots i look closly to correct this correctionovershoot.
What i tried to say is don’t be afraid to use aid settings aslong as you know the limitations and benefits. And test effects on your rawfiles. See if it’s doing what you expect. Never assume that rawfiles are bare storings of manual settings.
Electronics are quit smart these day’s sometimes smarter then we think. 
Peter
Found the slowshutter thing also: