I think you'd have to be pretty special to have a problem with the iD dropping out of the sky. I'd put this down to not being used to the kite and not being particularly skilled at flying kites (no disrespect, sorry)
The lines are specially designed for kites by a Dutch line manufacturer. They are Teflon coated high grade Dyneema. The Teflon coating stops ingress of sand and water which helps prolong the life although like with anything in a marine environment, if you abuse them, the coating will eventually wear off.
The iD was actually designed to fly on the rearmost front line connections. So fly the iD on the rear connections and move them forward if you want a bit more depower in certain conditions. (Normally I would never fly a Flexi on the rear connections as I only felt there was a benefit in doing this if you were over 90Kgs). The Hadlow iD is perfect on the rears and you can get a bit more speed and depower if you use the fronts.
Everything you just said seems true and is great to know! I like!
The 12m has a good low end I thought and you can "sine" it to get that little bit of apparent wind and lock in, powered enough for unhooking.
It is designed to be unhooked and will sit happily, providing plenty of pull to edge against with a firm bar pressure to keep it low and will give great slack after you pop for passing the bar.
Think of the iD as an easy to use Hadlow Pro. If you're serious about freestyle and want to progress then its perfect. (IMO)
Like with any kite, what you are used to will affect how you get on with a new kite and what you will like/dislike. Enjoy!