I posted some photos of simple and complicated repairs. Stitch technique works vey well for cracks between the seats. When you weld, you put the head casting through a lot of changes and it needs a complete rebuild and machining.

Usually the cracks can just be stitched cold, the valve job touched up and your good to go. It's very common repair for us on the magnum heads, they crack between the seats all the time. After stitching the heads are pressure tested and the resulting repair has been very reliable.