I have carefully done comparison testing of all digital scanners out there, and there really wasn't any doubt. I have owned all the digital scanners. For me, the GRE 500 & 600 are better at decoding p25, with better more life-like sound quality and less garbled noises, when put on the same antennas in the same spot. I remember how annoyed I was that you had to do the "tweak" to the unidens (press the knob, press this, adjust that, change this value, etc....) to get it to decode correctly. How dumb. The GREs take care of all this automatically, and always have. The 996/396 was better than the 96 and 2096, and then GREs came along and raised the bar, IMHO. Even more importantly for many of us, as a previous poster mentioned, the GREs do better with simulcast systems like the one I am forced to deal with every day. Take my word for it, there is a difference.
Don't get me wrong, I just bought a uniden bct15 and psr-400 for testing with outdoor antennas, and the uniden KILLED the GRE doing analog stuff, so I am no uniden hater. I currently LOVE my new BCT15, and will tell you NO other scanner can touch it on analog. I fully appreciate uniden scanners, and have for decades since my first bearcat.
I will also tell you the PSR scanners feel and look cheap, making creeking noises when held tightly, sometimes with loose duck antennas, and silly little displays that look horrible next to a uniden. They look and feel cheap and clunky next to a uniden scanner, but after extensive comparison testing, I use the 500 and 600 for digital, so there is my two cents. But this might not hold true for you...
As an interesting side note, every person has a unique situation, with all sorts of factors in play, that combine to create various effects. Combine this with different things that they are listening to, and you can see every persons scenario is unique. What this means, is that the ONLY way you will know which scanner does what best for you, in your unique situation, is to buy one of each of the competition, and do comparison testing. Yeah, it is going to cost you. You won't get back every dollar you spend when you sell the losers, but it is worth it to me, and always will be. I have to know I have the best tool for my particular uses. I believe the guy who said his uniden smoked the psr's on digital. I am sure in his situation, they did. Just as in mine and others situations, the unidens fell short of the GREs. There is no one size fits all answer. Do the testing, my advice.