Bonnie~
I have personally have not heard about quilting with todays threads and methods being detremental to old quilts. Unless maybe they were referring to being pulled and stretch tight on a hoop or LA.
I think that it is such a personal choice tho!
I am often commisioned to do the hand quilting on old quilts (Often found in trucks and closets) and I do indeed charge a pretty penny for the work.
And I have seen such beautifull machine quilting on others as well!!
Again I think it is a personal choice.
Whatever you decide please post pix when they are done (or even as they are now) would LOVE to see them!!
Patty