I don't think they would be an upgrade; no...just the opposite.
IMO the Energy RC70 is not what you want to get what you are asking for. They are not the best-sounding speakers around, by a long shot, IMO.
Since you have a sub, the ones I would recommend are the Wharfedale Diamond 10.1 speakers, which are only $349 per pair.
You might find it helpful to read the Stereophile review on them. That should help you to consider whether they are your best choice.
For nice mids and highs, and the resultant image quality, I think they are some of the best for under $600.
Edited by commsysman - 5/17/13 at 5:02pm