I've had more than my fair share of experience with SG warranty.
1. Badly torn up 7400 bag (100% my fault). Replaced the entire bag with a lightly used one from the return stack at no cost.
2. Strap stitching (bag attachment point) came lose on a first gen Krux frame. Repaired promptly, and all current versions are now bar tacked in that location.
3. Blown seam on a shoulder strap. New ones sent out next day without having to return old ones.
4. Bottom velcro that holds the frame rods in went out on a first gen Krux. SG offered to repair at no cost or replace with a current version for 20% discount. I ended up doing the repair myself for about 15 minutes of effort. Current frames have more re-inforcement in this area.
5. First gen Solo bag had an internal pocket seam let go. Instead of repairing, they sent me a current version Solo.
Turn around has always been very rapid and communication good.
The only thing I had to pay for was a lost sternum strap. For some reason the original I had was always working itself loose. The new one looks identical, but no longer comes loose for some reason.
As another note on their responsiveness. I had one of the first run of Sky 7400 bags. After using it for a couple trips, I didn't like the zipper configuration on the lid. I emailed them about it, and a few weeks later I get a package from Kurt with a handsewn prototype lid with a new zipper location. I'm still using it, and Sky lids have been built that way ever since.