FM is supposed to be better than AM.
75 MHz has more available channels than 27 MHz.
Digital trims, Exponential and Dual Rate Steering are probally the most important features that you would need in a computer radio. Everything else is just icing on the cake.
I personally have 2 Futaba 3PDFM's. But I've got so many cars now that I am going to get the new 3PK just because of the 10 model memory and ABS braking.
I'll pass one of my 3PD's over to my son.