Gotta go with bones on this one ~ I think there are more significant gains to be made by improving the front stage at this point rather than going with a different HU.
I will say this however....
If upgrading the head unit is the way you decide to go (if, in fact, you upgrade anything at this point) search through the classifieds here as well as on other forums. There are more than a couple nice head units floating around that people are trying to get rid of. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif