I'm a big fan of guitar supports. I've never tried the NeckUp, but I do have several flavors of the ErgoPlay as well as the Sagework/Barnett supports on both nylon and steel string guitars. They're all great, but the Sagework is definitely the cat's meow. I do have a footstool as well, but it rarely gets used.
I used to have all kinds of back problems due to playing hunched over. Guitar supports definitely allow me to play longer with less fatigue. Just do it.
Strings by mail has a pretty decent selection.
https://www.stringsbymail.com/guitar...-supports-386/
Bradford Werner has this review up on YouTube which is a decent overview of several different models.