I do tend to use down bags but I have to say that sometimes when it's not really cold but possibly quite wet I do pack a light/cheap synthetic bag instead. If it's a trip of more than one night I sometimes find I can get a touch paranoid about a down bag ... there isn't always the option to dry the thing out during the day.

Anyone else suffer from 'down paranoia'?

I use as synthetic mt hardware lamina 20 mainly because I am a hot sweaty sleeper and find it the right size when packed down.
I used down a lot when I was younger and hated the the cold & lumpy spots although down has come along way in the last ten years I still prefer synths even for my home duvets
but the main attraction is being able to wash it more and easier, my lamina 20 was not cheap and I have seen other bags that pack down real small for big money how ever i don't have big money.

who else uses synthetic and what do you have??

I mainly use down, but also have a Mountain Equipment Sleepwalker for wet damp conditions. It's not a bad bag, but the packed volume means I really think twice before taking it anywhere. Unless it's days out, I just take care of the down bag and pack it carefully in a drybag.