Line of questioning and detail requested from who? Would be good for everyone to know if you do get something in writing though as that's hard to dispute. What they say over the phone and what they put in writing can vary greatly!
At the end of the day though, insurance companies are not in the business of paying out otherwise they would not be in business full stop. Regardless of what an insurance company says they cover or don't cover, if on the day they decide they don't want to pay you out that's the end of the story. If your car is completely totalled how are you going to be able to argue that one of your mods wasn't the original cause of the accident? That's the line that they used on a friends BMW that was wrapped around a pole. Thankfully he only came out with a broken arm.
This is the risk we take by modifying our cars outside of OEM specifications. Gambit is the most recent success story, he had quite extensive mods done to his car yet was still paid out by Shannons. I highly doubt every single case will be that lucky.
EDIT: Sorry Gambit I didn't mean it was a success that your car was written off

I just meant successful claim!