my homespun raggy quilts have held up for 5 or 6 years now- they get softer/cozier each time they are washed-just like flannel
i've had no issues with them- i've made a number of homespuns quilts- raggy and regular pieced- guys love homespun quilts! all 3 of my brother's requested them after seeing my first one-
i usually double stitch my joining seams on raggy quilts-just because--the zigzag seems like a pretty good idea too- maybe i'll try that the next one. i generally double stitch so if one stitch happens to get clipped during the clipping process chances are the second seam will still hold- that way less chance of having any holes when it comes out of the washer the first time.
when i've had homespuns that seemed really thin i have backed them with muslin- but that hasn't happened very often-once in a while i will find one i really like and want to use but it is just thinner than the others- the muslin works beautifully-and when the quilt is finished there is no way to tell what squares may have that extra layer.