I still dont understand why on-one's all have 74deg seat angles, cotic have just dropped from 73 to 72 in acceptance that in-line posts are what your stuck with for dropper posts.
It's quite neat that Cy is building for people who care lots about their seated position on the flat, and run dropper posts.
Dimensionally it makes a lot of sense what he's done there.
Frame design is often a lot about joining up the dots, and that makes sense.
Since the Planet X Compo, way way back, I've always liked steep seat angles and shortening reach from the back. So that bikes climb well. I like Reverbs as they put people forward in the pedals. I'm not a massive fan of long seated positions with you arse too far backwards.
The Codeine (and the Ti Fireline Evo) also has a straight seat tube, a nod to people who don't have Reverbs and want to run a conventional post and drop it down in the frame for descents.
The Codeine also is a full suspension bicycle, where a steeper seat tube angle helps give rear wheel clearance under full compression. Slackening the seat angle would limit rear wheel travel.