On tenor, smoother sound than a Conn or a King, more spread than a Selmer. Big, colorful sounding horns, I wouldn't say dark, though, but not bright like a e.g. Yamaha. Tons of room to push, though, and a great for texas tenor. On alto a more open sound than Conn or Selmer, crisper and less refined than Selmer, usually. Bari -- big crisp sound. Awesome horns if you can live without the F# trill key.
Also the scale on the The Martins is probably the best of all vintage horns IMO.