I'm not sure how my Winterlite compares to the newer models, as mine is not even branded One Planet, but is branded J&H (who merged with Aiking to form One Planet, I think?). It is about 20 years old, or thereabouts, and I finally
tore a hole it in this year, so it's done very well for a very long time.
I've found it to perform very well, having slept in some very cold conditions, including the verandah of Kiaora Hut in the snow, and I've never been cold in it. 90% of the time, I don't even close the zip on it, to avoid getting too hot. I've only ever used the hood twice, and the neck muff 3 or 4 times, as the rest of it is so warm, I have to let out body heat somewhere, most times I use it.