Ah, the H46 (assume 36 was a typo). I've used it and it needs to fit perfectly in back length, because it's not adjustable. As you surmise, moderate loads only but up to the mid-30s [edit--meant to say the mid-20s because 30# is too much for the hipbelt, which sags] the large (medium in the real world) is very comfy. And yes, it's very light.

Provided it fits, it's a good, smallish pack for 2, 3-day trips.

Cheers,