Never liked the Norgie, it always made me feel like I was being choked, I think it's due to my short neck. The new shirt has had mixed reviews, mainly bad from those who had Norgies but good from those who didn't, but the new one is very different material and design, so you pay's your money and makes your choice.
Personally, I layer up with ECW shirt, t-shirt, Shirt/Jacket, Smock and if it's really cold I break out my woolly pully and/or fleece (civvy down one or mil issue one) and never really suffered from cold - mind you I wasn't issued on of the new ones either.
You might be able to pick a new one up cheap through a surplus shop, so you could buy on and do a comparison. But if you're happy with your old one, keep it until it's worn out; they're still a great bit of kit (if not my personal choice).