In talking with a local electronics store that's the local Radio Shack repair facility, their opinion was the GRE scanners are better for professionals who may use the scanners on tracking local radio calls on trunked systems. If someone traveled, then the Home Patrol may do OK picking up frequencies in the big cities.
However, Nashville, like many major cities, has made using mobile scanners that pick up police frequencies illegal. (Now, enforcing the ordinance may be a problem.) The emergency services I am affiliated with use VHF High Band and UHF 460 MHz, so I don't want to deal out $500 when the same amount of money will get me mobile and portable radios.