The GPS actually works really well, and if you live in a larger city being able to lock out the false alerts is awesome. So if you live in Chicago yes the GPS is worth it, if you live in rural Arkansas probably not. But if you do mostly highway driving without alot of falses the 8500x50 will do fine.
The 9500ix is a good detector. The Zr4's are weak jammers, if you have a small dark colored car you might do alright. But I recommend getting the Blinder M-27's they are about the same price and work alot better. Also if you are going to use either, a coat of Veil on the headlights will really help your jammer preform alot better. The Blinder-Guy has a special on his website where he gives you a free can of Veil with any new Blinder purchase. Blinder Xtreme Laser Jammer M27 and M47 (Blinder-Guy)