The Caledonia takes the same slot as the C had, but is quite different as mentioned, with changed geometry and bigger tire clearance. If you can swing it, have it assembled from the beginning with a one-piece bottom bracket like BBinfinite. It will also handle quite differently from the Topstone Carbon, which has rather odd geometry.
Also please note that because of the Topstone’s offset rear wheel dish, you can’t really swap wheels between the two.
I have a custom steel on order for when the new groups are available, which will be heavily cribbed from the Caledonia. If I didn’t, it would be a race between the Caledonia with a great BB or the Allied All-Road in the chameleon paint. Not cheap, but
.