I bought the Holton Eb in March. It's definitely very well assembled, and plays very nicely (much better than I can play it, but that's not saying much). From perusing the facebook frankentuba group, it seems that it was definitely made by "Victor Herbert": he posted a picture of this specific tuba ...

Since this tuba is still available (now discounted to $400) and since I just signed up for the forum: I was the previous owner of this tuba, before I sold it to Dillon in March. It plays well for a small Eb (I'm mostly a trombonist, but I bought this tuba 10+ years ago to play with my marching ...