Alright, I've just tested both Celianna's Futuristic Tiles and the Sci-Fi Tiles together. I don't have time to edit the two packs into one set, sorry, so basically I just created a Tileset with Celianna's tiles at A1, A3, A5, C and E, and the Sci-Fi tiles everything else.
Overall, not bad! I plonked a bunch of them together on the same map. With some careful tile choices, they could go together. There can be some clashes because Celianna's set has more muted colours and the Sci-Fi pack has some very bright pieces. But if I put both together, I don't think you can tell the difference with a casual glance. Edit: Forgot to mention that among the things that do tend to clash with Celianna's set is this blue chamber thingie and the bright purple rocks.
I would post a screenshot of the map, but I don't know if that's allowed.
I'm loving the Sci-Fi tiles btw. It's certainly inspiring me to create yet another game ;P