First, I agree with you that I, too, would choose walking the Portuguese over the Francés starting in Sarria. Having walked both the Central and Coastal routes let me suggest how I would combine the two if I wanted to get something from both. With 10 days available to walk, I’d begin in Caminha and go up the coast to Vigo. From there, cut in to the Central and meet up with it in Redondela. Just after Pontevedra, I’d suggest taking the Variante Espiritual which will again bring you back to the coast at Vilanova de Arouza where you can catch a boat to Padron and then finish your walk on up to SdC. As I count how we walked these stages, it would take 9 days. If you do have an extra day at the end, take a bus over to Finisterre. Bom Caminho!