pictures on the Amazon site for all three version seem identical in size.
https://www.amazon.com/Cuisinart-Steam-Convection-Stainless-Steel/dp/B01JRT2WOG
if Cuisi made a larger oven version of the CSB they would be stupid not to call it the CSO-400 or so.
I think there will be very little real into on the changes until current stock of the product is depleted.