I have 2 carbon wheelsets: Astral Wanderlust Carbon w/ DT-350 and Farsports 45mm w/ DT-350. I also have a few alloy wheelsets, including a set of rim brake alloy wheels around 1600g for the set.
I ride around the same speed as you. I frankly can't tell a significant difference between carbon & alloy wheels once I'm used to a bike.
A wheelset around 1500g feels nice, but once you get used to them, they're just like any other wheelset imo. As an extreme example of this, my 20inch alloy wheelset on my mini velo probably weighs around 1400g, with 400g tires. With smaller diameter, it should mean that moment of inertia is quite a bit lower. I still struggle at some start and stops on the mini velo. I don't feel like I accelerate faster on the mini velo. Although, I guess I haven't tried carbon on my mini velo...
The part that prevents me from saying that you shouldn't buy another wheelset is that you're signed up for some races. Go for it, if you've got the money and you want to set some personal records and push yourself. Go for deep rims if you're wanting most performance. Aero > Weight in most cases.