I ran Truvativ Noir carbons on my hardtail, and it did feel more comfy when using a rigid fork. No noticeable difference with suspension forks, mind.
Swapped out alloy bars on another hardtail the other day, and ended up with numb hands on the test ride. It turns out I had got my brake lever position a little wrong, and as a result I was stretching my fingertips to reach the levers to brake, which stretched my fingertips against the ends of my gloves. Removing my gloves got rid of the tingling, but movimg my levers about a quarter of an inch towards my natural hand position on the grips, and five degrees towards the horizontal more, helped even more.
Moral of this story: check it’s not your hand position. One more thing: if you really get on with a specific aluminium bar, but want something more comfy, see if there is a carbon version of that bar.
Can’t use my noirs on the new bike, as I need flat bars, by the way, so I am going to sell them.