In short, feathers offer the best combination of warmth, compact design and low weight. For the same weight, a product with feather insulation will be warmer than a product with wadding insulation.
That said, feather's worst enemy is the damp. If you go trekking somewhere damp, you may well discover that feathers don't like water. You may have experienced this already: when you wash a down duvet or jacket, it looks like all the down has been lost in the wash.
Of course that isn't the case! But the fine feathers contained in your product have clumped together because of the moisture. Tumble dry your product several times on a low temperature, short programme with tennis balls, until it regains its fill power.
It isn't recommended to go under the rain or in a damp environment (jungle or other) with a feather product, the insulation of your jacket or duvet could be reduced to nothing.