It's only the DVD with "The Tall T" on it that you have to keep as all the other material is in the Blu-ray set.I'm sure you won't be disappointed. Seven Men is alas Paramount and god only knows what if ever anything will ever stir from their deep catalogue again. Is Andrea Kalas still VP Archive?
Keep forgetting to mention this: THe new box has a fabulous run of extras and a big booklet but they couldn't get the rights for Dave Kehr's excellent feature length doco from the Sony DVD boxset, "A Man can do That". So keep the Sony DVD boxset for it.