I talked to Joe at ZPacks and am ordering Cuben seam tape and going to tape mine myself. He said it should take about 6 of the strips he sells and that you just need to put the bag inside out after removing the frame. (or you can ship it back and they will do it for a small fee)
I've had one minor stitch already go on the shoulder strap (my fault for swinging the bag improperly instead of using the haul loop). So reinforcing the stitching as well as waterproofing is worth it to me. It adds an ounce, but then if i can leave my pack liner behind, I save an ounce, to make it a wash except that my bag is now easier to pack.