Here is how these two sleeping bags compare on the numbers. Both are solid; the right one depends on the specs you care about most.
| Therm-a-Rest Vesper 20 | Zpacks Solo Quilt 20 | |
|---|---|---|
| GearScore | 91✓ | 69 |
| Comfort rating | 32 °F | 30 °F✓ |
| Weight | 19.0 oz | 18.3 oz✓ |
| Warmth-to-weight | 7.1 /100g | 7.7 /100g✓ |
| Packed size | 3.1 L | n/s |
| Fill power | 900 FP | 950 FP✓ |
| Price | $460 | $419✓ |
| Fill | Down | Down |
| Style | Quilt | Quilt |
| Shape | Quilt | Quilt |
Highlighted cells mark the better spec: Vesper 20 in blue, Solo Quilt 20 in amber. A blank spec is never counted as a win. A lower comfort rating in °F means a warmer bag, so the warmer bag takes that row. GearScore is the overall rating (0 to 100); re-weight it on the full bag comparison. Prices are current MSRP.
The Therm-a-Rest Vesper 20 against the Zpacks Solo Quilt 20 is a study in priorities. The Vesper 20 wins on balance, and the Solo Quilt 20 pushes back on warmth and low weight.
The Solo Quilt 20 is warmer (rated 30°F vs 32°F), 1 oz lighter, and stronger on warmth-to-weight. On the default GearScore the Vesper 20 leads 91 to 69.
Pick the Vesper 20 if you care most about the overall package. Pick the Solo Quilt 20 if warmth and low weight matter more to you, or you are focused on colder nights and shoulder-season trips.
The Zpacks Solo Quilt 20. It is warmer (rated 30°F vs 32°F) than the Vesper 20.
The Zpacks Solo Quilt 20. It is 1 oz lighter than the Vesper 20.
The Therm-a-Rest Vesper 20, 91 to 69 on the default algorithm. You can re-weight the factors to match your trip.
It depends on your priorities. Go with the Vesper 20 for the overall balance, or the Solo Quilt 20 for warmth. The spec table above shows exactly where each wins.