What is the application? Is this for a TT or some other type of trailer.
I have had both and found both to be good units. The P2 is for 1-4 axles, allows for 360 degree installation, and is for either electric or electric over hydraulic. The Primus IQ is for 1-3 axles, allows for 70 degree installation, and is for brakes electric brakes.
My preference would be for the P2. I like the manual arm better than the push button on the Primus IQ, and the LED is easier to see at a wider variety of angles on the P2. I'd say if money is tight, the Primus IQ will perform very well and is a quality unit. I would not have upgraded if we hadn't sold the vehicle with the Primus specifically wired for it.