This probably isn't the right section for this discussion, but I'll chime in...
Love my PRO-97. Works very well, lightweight, very readable display screen. Great frequency coverage (MILAIR, for one).
Only things I don't like are its size (it's bit bigger than my BCD396) and although it's every bit as sensitive, it isn't as selective. (Its squelch opens when very close (+/- 5kHz) frequencies become active.)
I've got a pro 97 and a gre 500 and to be honest, other than the digital features on the 500, I can't tell a dang bit of difference on anything else, weather, batteries, signal, chargers, keys, analog conventional and trunked system types, all appear to work the same, Digital and the LED/Backlight features are a little different also, That's it! No trouble out of my pro 97, In fact, it's one of the best scanners I've ever owned!!!
Far as the 164, Don't know much about them just that their similar to other Rat Shack Brands, That's about it..