I have used fleece liners on one trip, and it was a big mistake not testing it first. I can tell you right now that they do nothing for the wind. If a breeze comes by, it saps your heat. If you have some sort of wind-proof shell, you will need that. I was freezing for three nights, and I had two liners, was wearing a sweat shirt and jeans. What fun that weekend was (sarcasm, if you didn't already see that).