There are definitely better, more modern convertibles, but for a vintage lens the TR triple performs quite well. It is, of course, better corrected when using the 12" configuration. The addition of a yellow filter helps to sharpen the 21" and 28" back up. I have one that I use quite happily on 8x10.
Edward Weston shot hundreds of negatives with this lens, (IIRC he didn't like the 21" focal length) so if the lens is in good shape, you won't be able to blame it for much.