That's a very fine center. Does it never come with a grille? I don't see any photos of one online.
FWIW I own neither Phantom nor the Nautilus. The Phantoms, do they punch precisely? Everybody always talks about surround diffusion, but even with dipoles I locate everything exactly (my preference), and one thing I consider a must is precise bass impact when things fly overhead. Unless that is your gear is employed for multichannel music.
On topic I do like that Tekton offers colorful options, some of which come out almost ceramic in appearance.