Spending the money on a new head unit may or may NOT yield better reception. You can look at the specs all you want..but it may not yield better reception.
Check to see if you have any HD radio stations in your area (at least with the kind of radio station you listen to). If there is..then MAYBE buying a new head unit with a built in HD radio is good. I had a problem with my radio..so I bought a new one with built in HD...The cost difference between one with built in HD and not was minimal ($10). The HD stations I listen sound FANTASTIC...Wish I switch to an HD radio sooner.