Times change... New models come out... Thats all there is to it.
I have a 785D and love it, great receiver. What are you looking to monitor? If its a newer trunking system you might need a newer model such as the 796D, i have one of each. The 785D only does 3600 baud control channels, so if your monitoring trunked stuff make sure it will work for you.
If your going to monitor convential channels, even digital if it has the optional card, you can't beat the older 785D for that.