Nothing wrong with it, just it's way more bulky. When you put the insulation in the jacket it works better and can be thinner. Yes you loose some versatility but you also don't have to be zipping liners in and out.
I think she'll use is tied a lot more to two things. Cost - only one jacket; style. Cost needs no explanation, but style usually gets muddied with things like " it's better", " " it's more efficient".
Here's a question for the shell people. Why are some warmer than others if both are lacking in some sort of reflective coating or the like? We switched shells this year and I find the new one much coldr wearing the same stuff underneath Is it the warmer one is more breathable than the other?
Interesting hat not all shells at the same warmth.
My Mountain Hardwear Keplar is not as warm as my Beta AR's (I think) because the Dry Q fabric doesn;t use entrapped heat to vent moi"clammy", with clammy only being a relative items compared to the Dry Q.
But yes, I've noticed it too, and the Keplar is made of a heavier fabric than the Beta.