So far it's been unanimous. Everyone I've heard talk about it believes Strawberry is mainly just CoT. I'm not saying they didn't fine tune a model too, I'm just saying I agree with most people that clever CoT is where most of the leap in capability seems to have come from.
I haven't even added Strawberry support to my app yet, and so haven't checked what it's context length is, but you're right that additional context length is a scaling factor that's totally independent of whether CoT is used or not.
I'm just saying whatever they did in their [new] model, I think they also added CoT on top of it, as the outer layer of the onion so to speak.