Huge matter of differences with the fellow ranting here. We were focusing on C&V, plus I highly doubt its a common occurance that we carry cast iron V8 engine blocks.
I'll try to be brief. But just as a reminder and not to slight any manufacture, often makers have price point different models. The Santana Arriva mentioned caters more budget price point and a very popular seller. While at it, that company offers frames in steel, aluminum, titanium and carbon fiber. Let's keep going............ select triple, quads or hex.
The ranting dude knows nothing about the exclusive specific tubing made for them way back, frame design, fillet brazed, head tube specifics. The coined name Marathon has some real meaning. It makes no economic sense to keep making them like that again. That's all. I've had C'dale ally and clearly know the characteristic differences.
Then the issue of forks comes up. Back up a bit to vintage. There was a time that all bikes used a common 1" steerer. That does not make them bad. Millions are still around today. There's some great vintage tandem forks too. Twin plate crowns, some quality cast types.... nothing wrong with having them today. He's making it seem as if their failing left and right. I happen to like the nostalgia, style of these. Also, good for one if they like the looks of a shapely fork, unicrown, this or that.
BTW: Not vintage but thought I'd share a few pics of state-of the -art brand new, STEEL frame, top tier hand made by someone who you should well recognize.

