the only person that can answer this question is yourself.
Are you happy with it?
Then yes it was worth it.
Do you feel its the best upgrade you could of done at the time?
Then again yes it was worth it.
Were you expecting a hugh increase difference between the E6850?
Well that is a iffy, did you oc the E6850?
Do you want a cookie for the upgrade?
OK here's a cookie.
But seriously, no one can tell you if something is worth it.
We can tell you if ur stupid for side grading instead of upgrading, but this doesnt fall in your catigory.
You built a good system, and most definitely an upgrade from your previous, so i would say its a well built system.