I have both, and...
I have the Radio Shack PRO-106 (PSR-500 equivalent) and the BCD396T.
They both do very well on P25 systems and both decode very well.
I recently took the 106 with me on a trip to an urban area with lots of RF, but (ignorantly) I left the 396 home. The 106 absolutely crashed on front end overload. I was really disappointed, but more with myself for not having brought the 396T to see how it handled the same environment. I'll be making a return trip to the same area in January and will bring them both so I can do a head-to-head comparison, but I can't imagine the 396 doing any worse (and from a simple test in my ham shack, the 396 handles a nearby transmitter a lot better).
The 396 is a LOT smaller and travels better, and the case plastic is harder and has a better finish. The 106/500 case looks to be cheaper plastic, and it is more vulnerable to scratching.
I like the 106/500's display better (it's bigger and clearer).
The 106/500 seems to scan faster.
The 396 belt clip is a LOT better.
They seem to me to have equal sensitivity on all bands.
Both have good receive audio, though the 396 seems stronger.
The 396 has quieter audio (there is a notable hiss on the 106/500, particularly in the aviation band).
Other comments:
- I far prefer the 106/500's 4-battery shell design to the 396T's three battery design. My charger does four at a time, and when I am on the road and using alkalines, with the 396 I end up with these odd batteries I need to keep track of. Also, I find it far easier to pop battery trays out and in on the 106/500 than replacing individual cells on the 396.
- The 396 SMA connector is well designed, but I like the BNC on the 106/500 better.
- I far prefer the traditional separate and directly accessible controls for volume and squelch on the 106/500. I don't like having to press in on the 396's knob to activate the menu-driven volume control. I like even less having to do the "F" and press-in step to adjust the squelch.
- I like the programmable multi-color LED on the 106/500.
- I like the easy-access 1/8" 106/500 programming port better than the rubber-covered 396's.
Both are very good scanners, and I am happy with both.