It depends on the garment if mohair is flimsy or not. Specifically, the size of the gauge. My 1st knitted garment was a mohair sweater. Way back in the late 60's when they were the "in" appearal item. It was not flimsy at all. And warm....whoa! Knitting a fine mohair on #15 needles would be flimsy, but so would any fine yarn. Plus, using even a lightweight merino or alpaca will change the gauge of the yarn blend. And just try matching the colors. Then there's the change of the drape. Mohair drapes wonderfully, change the yarn, change its characteristics.