need your opinion on down sleeping bag :)

still looking for help here

There are many good brands.
Buy on brand rep, not on price.

Cheers

"3. durable" One solution would be to use a tyvek or nylon ground sheet underneath your pad to protect your sleeping bag, instead of a heavier fabric in the sleeping bag.

On the other hand, FF would probably custom build a bag with whatever outer fabric you want.

I'm a little confused by "…can be highly humid (desert)"; my understanding of the definition of "desert" is that it's very arid, which is the opposite of "highly humid"…?

I hike in rocky/rough terrain and also prefer to cowboy camp when I camp. I just take an over-sized groundsheet to better protect my sleeping bag and my pad.

What about a Big Agnes bag with a built-in pad pocket? Solves the issue of rolling off your pad.

Sumi:
desert in Israel can be very very humid at nights. waking up with wet sleeping bag is common here

sounds like ground sheet is the solution for durability.

Cheapest groundsheet is anything laying around, but a good option for a groundsheet is Tyvek. I use the kite-making Tyvek over industrail Tyvek, it is a little thinner and it doesn't have the guild-inducing DuPont logo on it. Check Amazon for kitemaking fabric by the yard for under $10.

Personally my next bag will be DWR treated down. I believe Marmot sells DriDown bags. Yeah, I love my WM Megalite but I would love it a lot more if its down was DWR treated.

DWR treated down is relatively new and the main advantage is that the treated down absorbs MUCH less moisture and thus retains loft better and does not gain much water weight over many days of use, particularly in damp conditions where drying the bag may not be an option.

Marmot, Patagonia and one other company have proprietary DWR down treatments. Patagucci's method of DWR deposition may be the best one. Time will tell.

?מאיפה אתה בארץ

I miss hiking in the Negev…I did Shvil Israel 2 years ago. I didn't notice too much humidity, although it was in March, not summer.

I imagine it's pretty expensive to get quality gear over there…none of the local manufacturers make anything ultralight, for sure.