PJ,
We shopped a Decathlon in Burgos while on the Camino. I guess I have two somewhat contrary impressions: 1) it really was the best I saw in Spain besides that great backpacking store in Astorga; 2) it does not really compare to the quality we can get in the states. Sort of high sales volume, middling quality products. On packs, you can get much lighter, and better packs. I have never tried in France, but from the internet it appears that IGLOO SAS SPORTS in Toulouse carries some Osprey products. Also look for an Exped dealer (I think they are a German company). And the American cottage manufacturers are (IMO) making the best packs in the world right now. Look at Zpacks, Elemental Horizons, ULA. They have no dealers--you just order online. Even the REI flash series I think is better and lighter than what I saw in Decathlon. That being said, lots of people (especially the Spanish) carry the Quecha packs. But I would not--too heavy.
Buen Camino,
Jo Jo