OP: a 20F rated down fractional UQ can be squeezed into the Clark stuff sack, which are all the same size. Not with the Clark XL or Vertex rainfly, too; but then, a dew-damp tarp shouldn't be in there anyway.
A 0F UQ? No way it fits with an NX250. And, please use the search facility here on UQs in the appropriate Forum for many other opinions. IMO, even aside from the convenience of one less stuff sack, the 0F UQ is over the limit in bulk, in the way for warm, muggy nights, a bridge too far; and so rarely needed even in winter in PA. IOW, don't make the mistake some do in selecting a sleeping bag: getting "more for your money" and bragging rights by buying too much. A 20F fractional UQ can be compressed enough, to mushball in bulk, that you'll find a place for it.