Peter, thanks. I wondered if one was a thinner (less warm or more breathable version) of NeoShell.
I would say Westcomb sizes pretty big. Or at least not smallish.
I'm 184cm, 72Kg (6.1" / 158#) and have the Medium. As often, I'm right between a Medium and a Large and depending on the brand I go for one or the other. With the Westcomb I went for Medium.
The Switch has a dropped tail (lower back than front) and with the Medium the sleeves come down to my knuckles. The back hem line comes down right to the middle of my ass.
The Large would be ok for me too, allowing even more coverage/heavier layering – but I personally didn't feel I needed it.
If I roll it up loosely in its hood I think it's slightly larger than a 1L Nalgene? (see photo with centimetre measure).
In a stuffsack or whatever I guess you can get the volume down to 2/3 or roughly half of this, but I like to keep it rolled loose on top of my pack.
It's not a super compact, ultra light shell but it feels very durable, breathable, and non crispy chips. Mine weighs 430gr. (compared to 262gr for my Large Marmot Super Mica for example, which I feel is way more fragile and that I use for just in case, bottom of the pack, hot humid summer situations).
When I speed hiked up the mountain in moderate rain with an iPhone in the inner pocket, the iPhone got wet from the moisture being wicked from the inside. I personally do really like pit zips, because a hole breathes better than a fabric and Japan gets really really humid.

Hope that helps a bit.