Well, I liked the slow pace of it, and the teach tree was good, although it could be bigger. I'm happy for it to be set in space, or anywhere. I've heard that most 4X games are turn based, which I'm not a huge fan of. I would prefer the game to be real time.
With the combination of slow pace and a large tech tree, you are definitely into turn based 4x territory, if you haven't played a Turn-based 4X game before which is what it sounds like, then i can asure you they don't play like the turn-based tactical combat games. That said, they can be Time sinks expect to spend alot of time on them. My personal recommendations for Turn-based 4X games are Civilisation 4, Galactic Civilisations 2, and Sword of the Stars (all with all their respective expansions)
Most RTS games, perhaps obviously, lean towards fast pace, which usually limits the visible tech tree, if you can put up with the fast pace though the RTS with by far the best tech tree is Earth 2160 (few years old now but still a damn fine game), of real time games that incorporate 4X elements the best is probably Rise of Nations, again fairly old, but still very good (and better than Rise of Legends its spiritual sequel).
See the problem is because Sins is a borderline game between the two genres there are few examples like it, Imperium Galactica 2 is, as has been mentioned by others, probably the closest you are likely to find, it has a much more engrossing tech tree, as well as some additional gameplay elements (Ground Combat, on-planet base building, more economy micromanagement, customisable units etc), So if you can find a copy its well worth getting.
Apologies for the long post.
