My take on the matter is simple. Synthetic bags are great when you first get them, but they don't last. My wife and I bought REI down bags when we got married in 1975. The bags are still excellent, toasty warm.
Back in the 1990s my wife bought me a top end synthetic bag. Oh it was great the first year for snow camping, but the next year I noticed the insulation properties had declined, and (un)down it went from there. It was a MEC bag, and they wouldn't stand behind the product.
I am new to the hammock thing, but I will save my pennies for a down UQ.