Also, extension causing "shock loading" and "significantly" higher forces has been debunked a long time ago. Jim Ewing at Sterling Ropes conducted load cell testing completely disproving the idea, showing there is almost no concern over small amounts of extension (a foot or less), that overall force was not increased during tests where a piece blew, and that "shock loading" is a vague term that doesn't apply to a system involving an elastic climbing rope.
Read Climbing Anchors by John Long. All that testing is in the book, the book which starting all this new anchor discussion.