It will be a great upgrade from the E510 with lots more features & buttons too. I'm sure you will love it & you should get used to the weight increase with the comfortable grip. Your 14-54 lens is weather proofed & having the body to go with it, will give you the possibility to try it at times when you wouldn't take your E510. Another camera that will be interesting will be a higher level (prograde possibly) micro 4/3 body later this year, but those with a preference for the optical view finder will probably take longer before they will change to that (except as a 2nd camera).
I wish you well with whatever you end up upgrading to & I think Olympus has a few more things up their sleeves for this year, so should be interesting seeing what will be on offer.