No bag is warm when totally wet, but synthetics can be wrung out and dry rather quickly whereas down remains a heavy heap with no loft for days. I have always used a down bag, even 35+ days with only a tarp and 28 of those 35 days it snowed! You have to be extra careful with the bag- I always pack it away even during the day in a waterproof stuff sack. And you have to take every moment of sunshine as an opportunity to dry it out. I do not recommend down in wet condtions for beginners, but I think experienced people can handle it.

There are much better synthetic bags out there nowadays. The old ones used to be very heavy and bulky- some of the newer ones are nearly as compact as down. Look for a high quality synthetic bag - will probably cost you several hundred dollars.

I also use a single-wall tent and although there is condensation, I have never had it truely drip. I am just careful not to rub the bag against the inside wall. A bivy sack will also produce condensation inside so you still have to air it out often.

I always take a small high quality sponge with me. It is really handy to wipe up condensation.

In the winter I have used a combination of two summer bags- larger outer synthetic and smaller inside down liner. I like the way down really fills in around your body and makes you instantly warm.