Other luggage with lifetime warantees
While not particularly glamourous, and you'd have to see if their luggage is suited to your specific needs, I would recommend both Patagonia and LL Bean. I have had the "burrito suiter" from Patagonia replaced twice with no problems whatsoever. Additionally, I have had returned a laptop bag to LL Bean where the handle became unstitched, and the item was replaced with no hassle.
Hope that helps.