you're welcome stayat home, i did sew the hearts on after slashing and they stayed just as flat as could be most every time. a couple of spots caught the slashed fabric but after washing you can't even tell. the stitching lines for the chenille are only 1/2 inch apart so there isn't much loose material.
are you going to go for the chenille?? try it, its pretty fun. you can even do it as one large block. just sew diagonally across the whole area with 1/2 inch between the stitch lines. use at least 3 layers, maybe 4. it makes a very nice baby quilt with no blocks to join.
good luck, post pics if you do one of these pretties.