The most important factor should be considered is the usual temperature in your bedroom.
If your bedroom is not air conditioned then the temperature could fluctuate with season. So it is best if you choose the season in which you would like to sleep in the silk comforter first. There is a general guideline. For a bedroom at 20c, a queen size comforter weighting approximately 1kg/2lb should best suit your needs. With every 3c degree decrease, add 0.5kg/0.9lb to the weight of the comforter. So if you are experience to sleep in a bedroom with a temperature of 14C in the fall/winter season, the comforter should weight approximately 2kg/4lb. Of course ,this is just a rough estimate and only used as a reference.
Always protect your comforter with removable and washable comforter cover. Your silk floss comforter would not need thorough wash for a long while.