okay, i dont usually do this, but its something about this post...
we dont need to know all the games you've played... i dont think anyone cares... its a forum, not a job interview you dont need to bring your CV
its a forum about Sins of a Solar Empire, not showing off all the games you've played and what internet sites you run and how you cant use the return key on your keyboard
also, hmm, a thread in a forum dedicated to Sins of a Solar Empire, you call your thread Sins of a Solar Empire... wow, how very descriptive and very informative to the forum-goer
You should have titled your post: Interested player, should i buy this game. and then skipped your credentials, its not like you need to prove yourself, and then told us the things like you prefer Battle.net and UMS, even though they are not really necessary.
anyway, thats my rant done
now, cause im a nice guy, and cause i dont want you to get the wrong idea about the kind of people who play Sins and who usually come on these forums, i want to apologise for the rant (its just stupid/ineffecient threads tick me off) and i want to say your should definitly get the game
even if it isnt UMS or Battle.net style whatever, its good in its own way.
Now, you seemed to have an interest in MP, well, this game does not have a Campign, only skirmish mode and Online Multiplayer vs AI or other humans or both. That said, most people seem to prefer SP, (though there is a rather dedicated MP group with clans etc) despite the lack of a storyline.
However, if MP is really what you are interested in, then its basically the same as SP, but harder due to human opponents. in fact, you could train up as a new player in SP against the AI, then move to MP and be alright (im saying alright because most Sins players seem to use optimised build orders and capitalise on the Rock-Paper-Scissors hard counter system, so, basically, if you come up against a pro early on, you will probably get nuked even if you regularly beat unfair AI)
I dont play MP that much myself so you would be better off asking someone like CenturionJixra about it.
SO, Sins is a fair bit slower than most RTS, because they tried to build it halfway between RTS and 4X. that said, its slower than RTS but faster than 4X, even though game speed is adjustable. im not sure about half of the games you quoted... mainly because they are just listed up there in a clump... but i have a feeling it may be too slow if you compare them.
Some people have compared Sins to Surpeme Comander (i think, dont quote me though) in terms of enjoyment based on style of play. ive never played it so i cant say myself. the best thing is to just take it as it is, dont but a game because its like that other game you played because then there is no originality.
lastly, i definitly think you should get it. i cant give you reasons such as "you should gget it because" because im not you, and i cant say, well, you like good graphics, so buy it" whatever. ive told you a bit about the game, and i think you will like it because 99% or people do.
good luck
EDIT: you also have a double post in the forums section. its not necesary, but etiquette would advise that you remove one of them