Nunatak Arc Alpinist with 4 oz overfill.

Big Agnes Insulated Air Core.

Gossamer Gear 3/8" ccf pad. Most of the time on the bottom, but move to the top when it gets cold.

But this is only part of the sleep system. You need to keep your feet, hands and head warm.
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"In theory, theory and practice are the same. In practice, they are not."
Yogi Berra