I have given some thought to your post before replying. I had a GRE PSR500, but sold it recently and bought a BCD396XT, In answer to your specific question, I think that the Scanner Master comparison is pretty good. Like DonS pointed out, you can actually get a few more conventional channels than published numbers. I, too, have found out that the batteries don't last a long on the BCD396XT. I don't know if it is simply an issue of 3 batteries vs 4 batteries, or if the BCD396 actually does draw more current. As far as real world examples, I am a deputy sheriff and use a digital simulcast system system at work. I have a Motorola XTS5000 and scan 15 talkgroups with it. I use the BCD396XT in the car to supplement the Motorola. As such, I am often comparing the audio of the BCD396XT to the Motorola and recalling how it compares to the PSR500. I have to say the 396 is very good. I am somewhat inclined to say that it is better because I seem to recall more times with the XTS5000 that it would be receiving a talkgroup while the GRE PSR500 was stopped on that very talkgroup and could not decode it. I really don't have that happen with the BCD396XT.
For me there are some other important features that the BCD396XT has that the PSR500 doesn't have. That is ENCRYPTED AUDIO MUTE. We do have some talkgroups that can have encrypted audio on them. I don't want to hear that noise. The Bearcat mutes it and the GRE doesn't. It is as simple as that. Also, the priority is huge for some people. A woman who retired from her civilian position with us came back part time and was asking me which scanner. We discussed it a bit and as soon as she heard that the 396XT has trunked priority and the PSR500 does not, the discussion was over. She dispatched for a number of years and still likes to listen. She said she had to have trunking priority.
The above having been written, both are very good scanners. Some things are pretty objective, like physical size, and really aren't subject to debate. You can debate how important size is, but the PSR500 simply is bigger than the 396XT. That is better for some and not so good for others. Other things are more subjective, like the 396XT sounds better or the 500 sounds better.