What is the bottom line on both the Liberty and the Unity? Well I would have to ask you a question first. Just what are you looking for in a radio?
If your looking to be able to monitor 2 bands at the same time, neither radio will do that for you. You would be better off buying 2 lower cost radios with one on each of the bands your looking to monitor. Reason being is that there is only one receiver in these radios. Sure you can scan both bands, but the first signal into the receiver will capture the radio and the second incoming signal on the other band won't be heard.
If your looking to only operate a single band at a time, then you have a number of choices. Buy one of these expensive toys at better than $5000, or buy 2 much cheaper radios and keep both with you. If you find out that only one band is going to be used, leave the other radio in your vehicle.
Having been on the front line for over 35 years with the fire service and working with public safety radio systems for over 45 years now, my choice would be a way to hear both bands at the same time. Most of the incidents that I have been to that had more than one band involved for communications had chatter on both at the same time. The only way your going to keep up with the action is to have 2 different radios or put a gateway in service and link both bands together.
Which is the better choice for you will depend on how the radio communications are used. With the tight budgets these days, I would take the route that provided the best communications for the least cost. My bet is that in many cases, the 2 radio move is better and cheaper.