I don't have much experience hanging in cold weather, so I know very little about quilts. I want to extend my hanging season, so I started researching underquilts. I think I have decided on getting an Incubator (or possibly a Crowsnest, jury's still out on that one). I was browsing the possible upgrades available from Stormcrow, but I was a little confused. Time to expose my ignorance!
900 FP refers to a higher quality down that gives more loft for the same amount of down. Wouldn't that mean that choosing this upgrade would add no weight to the uq, but would still lower the temperature rating by 5*F?
Overfilling is literally adding extra down, so I would expect that an ounce of overfill adds an ounce of weight to the uq.
Is what I just said correct? Are there any other pros or cons for one upgrade versus the other? Is it possible to add overfill to the 900 FP down uq as well? If so, what temperature ratings would that yield?