I have returned both bibs and a jacket, at different times and for different reasons, and both were replaced with the new version promptly and without question. On the bibs, the thread holding one of the straps came undone on way to the start of Pacific Cup, so I sewed them back up with sail thread. Even with my frankenstein-esq sewing, no questions asked, new OS1 bibs showed up in the mail.. On the jacket, this was very minor but annoying, the velcro meant to hold the collar shut quit working. I thought it was a stretch to get a new jacket out of that, thinking maybe they would replace the velcro. However, a new OS1 jacket came a couple of weeks later. In both cases these items were 4-6 years old and I couldn't be happier with their service.
Here is the their warranty statement:
PERFORMANCE WHEN YOU NEED IT
All Gill products come with the "Gill Guarantee". This means that you can trust a Gill product to perform whenever you need it to. The "Gill Guarantee" covers against all defects in material and workmanship which means that if, after inspection, the product is found to be defective (other than fair wear & tear) we will repair or replace it at our discretion, free of charge.PLEASE NOTE THE FOLLOWING:
Normal wear and tear will not be warranted. Neglect and mishandling of zippers will not be warranted.