Agreed with ST:O being crap. I like eve because of its complexity, and "risk" factor. As a certain captain once said "Risk is part of the game". However i do hear you on not wanting to invest so much only to lose it in a second. My toons are now carebears in empire building up a mighty warchest for my next 0.0 rampage. Embarrassing yes, but even suicidal psychos need isk too.
X3, or TC would be the way for you to go then. The mod community there is thriving. However they stick mainly to the X universe. There is little to nothing on mods for other genres. I was tempted to port HW2 ships into X3, but someone else beat me to it. Thank god.
The X series is very similar to Eve, but the risk factor is not near as high, and dead is not truly dead like in eve. As MyFist0 said it is single player. So if you die just reload a saved game. I kind of wish there was an "offline" version of eve.
Sins may allow for all of the things you mentioned, but it has some big flaws. It is 32 bit, and loads all of its game assets at once instead of on the fly like other games do. It is hard coded to dump when it reaches 2 gigs of ram usage. There are workarounds, but they are risky imo. We made TSOP to help with the 2 gig problem. The only "true" fix will be to rewrite sins in 64 bit. With multicore support. Which is not going to happen. Unfortunately sins is a good game that came out during a transition period between 32, and 64 bit tech.