I love knitting with tencel blends! I also love clothing made from tencel fabrics.
Tencel is such a lovely fiber and when blended with something like alpaca, angora, or cashmere is SO soft. It has the strength of cotton but better drape and it's easier on the hands to work with.
It has a really soft drape, so it won't be great for anything with cables and such, but if you want something really soft and flowing, I can't think of anything I would rather have.
When I knit up a little gown using a couple of stands of tencel that had a small amount of silk blended in and a thin strand of cashmere (from a recycled cashmere sweater) I kept going around to my family saying... feel this! Doesn't it feel WONDERFUL!
I have some of the Quechua but I haven't used it yet, so I can't address that yarn specifically.
I have done blanket squares from tencel/cashmere blend and both with the squares and the gown, it blocked up beautifully.
Ok... I'm gushing, but I really like tencel!
Here is a photo of the little gown, maybe you can kind of tell the drape if you look and see how it flows along the legs of the dolls body.