I use a Diamond discone antenna with a multicoupler that has equal outputs feeding all my scanners. Comparing them all on the weakest P25 signals, this is how they stack up:
BCD536HP
BCD436HP
BCD325P2
BCD996P2
Home Patrol
TRX-2
PSR-600
WS1040
It should be noted that the receiver sensitivity between all these models is not all that drastically different. They all have more than acceptable receiver sensitivity. The real difference between designs is how well they decode digital signals.
On the weakest P25 signals with Threshold settings maximized, the difference is hardly noticeable between the 536 and 436. Mostly lower signal bars on the 436, but still receives about the same.
The jump from 536 to 996P2 with manual threshold settings on both (9 on the x36 models and 10 on the P2 models) shows a bit more error rate on the 996P2 (example 80 versus 50), but still gets most of the traffic. Only some choppy signals on the x36 scanners are totally muted on the 996P2, but I noticed the 325P2 does a bit better with a slightly lower error rate than the 996P2. The x36 scanners have a better narrow band filter that gives them an advantage with lower noise (which means a cleaner digital signal), but I prefer the P2 scanners as they seem to scan faster and pickup more transmissions with larger scan lists. That is more important to me. I dispise missing transmissions! And I can only trim my scan list so much, as I focus on all possible frequencies that are known to be used (or potentially could be used) in my area by multiple government agencies.
So the GRE / Whistler scanners have slightly better analog sensitivity, but don't decode the digital as well. The TRX-2 will actually stop on P25 signals the Uniden scanners won't stop on, but it will be all "Donald Duck"...an expression we use to describe unintelligible digital voice. Though I'm happy it does that, as I can still capture NAC and often Unit ID data for my search efforts. I use Whistler scanners for searching, and Uniden scanners for listening (x36 and P2 scanners skip over P25 encryption if the channel is programmed as a "digital only" channel). The older GRE designed PSR type scanners hear weak signals, but struggle the most to decode P25. And if you live near FM broadcast transmitters, you will need to filter that out with an FM trap (the Stridsburg filter works the best), as VHF low and high bands get totally desensed without the FM broadcast signal being removed. They do one thing that I need that none of the others do, and that's decode and display the P25 NAC on P25 data transmissions. The TRX scanners show the NAC on data, but don't record it. And I understand why they did that. Who "normally" wants to stop and record data you can't hear? As far as my old Home Patrol goes, I thought about selling it, but it does scan very fast. At the firmware level it's at (maybe old now) it stops on clear or encrypted P25 signals and records the NAC. So I scan all the G band channels with the known channels avoided (skipped, or locked out), and just record anything new. That works extremely well...but still doesn't stop on P25 data...so I still need the old GRE to do that. Data can identify a user without any actual user voice transmissions being involved. Again, the right tool for the right job because no "one" scanner does it all.
There is a difference between "searching" and "listening", and neither company seems to understand that. So, depending on what you're looking to do, each type of model has its pluses and minuses. That is why I use them all. As each model is optimized and set to do different tasks, the complete multi-scanner setup can, and does, cover all the bases. I hear all the know stuff as well as it can be scanned, and almost instantly spot any new stuff, as it is being searched three ways.
Phil