I really love the sound you get out of these vintage horns-- they're earthy and mellow. I especially like the Martin altos, and the Buescher tenor was beautiful too. As an amateur and a starter (after playing clarinet many years ago) I'm curious about the vintage instruments: are they harder for a starter to play than the modern horns? By that I mean, are they more resistant, and is it harder to maintain a consistent intonation than the modern horns?

I started with a Martin Typewriter as my first horn, I dont really believe that matter if you have a good teacher. You get used to the horn

don't start with vintage horns. they are wayyy harder to be in tuned. Get modern horns if you are a starter and when your ears and techniques get better, grab one!