I use a set of Soft Shackles as a Biner replacement, have used them for two years now without issue! My set up goes: 4 ft. strap around tree- Shackle - whoopie
My whoopie stays attached to my hammock via larks head! I used to use Dutch Clips but when I was experimenting with the UL set-up that was one of the things that got cut from the line-up and just passed the strap through the loop!
I carry two suspension extensions as a just in case I have a tree that my 4ft strap won't fit around, works every time!
So far I haven't experienced what Hawk did, never saying it couldn't happen (as others have said the same as him) but I carry a extra shoe lace (cotton one, not waxed) as a just in case it's needed!