Well I for one did have some sensitivity degradation on a P25 700 MHz system after DSP 1.0. Current versions of the firmware are somewhat better but still not as good as DSP 1.0. HOWEVER, I NEVER HAD LOSS OF SENSITIVITY ON STRONG SIGNALS AS APPEARS TO BE THE CASE HERE-ONLY ON WEAK SIGNALS. And I never had any major loss of sensitivity due to firmware updates. I am currently using all the latest firmware.]
I am not really interested in reflashing the firmware. I am not so sure that it is a safe practice. My situation seems similar to that of "TheWenk", I have not noticed any "great loss" of sensitivity, it is still far more sensitive than the 396 which I owned for about two years. But, I did experience a noticeable reduction in signal strength. I just found it interesting to see someone else point out the same issue that I suspected, though Paul1's case sounds more severe than mine. Thanks to everyone for giving the situation some thought. I am not very technically inclined. If the folks at GRE are aware that the possibility exist for firmware updates to affect the radio's sensitivity, perhaps they can give it a look. For what I am experiencing, it is not worth giving up the cool features that GRE has provided, by reverting back to a previous firmware version.
A few more comments for what they're worth:
1- I've reloaded the old firmware and then loaded the new firmware many times while investigating this problem and I think it is essentially impossible to damage the 500 by doing this. GRE's release notes support the fact that you can't damage the scanner doing this.
2- I believe that GRE was/is aware of the P25 sensitivity problem and I believe they truly made an attempt to address this issue back in the days of the DSP 1.1 & 1.2 upgrades. Some of the notes for these upgrades specifically address improving P25 sensitivity. But I suspect that there was a compromise at that time where other "fixes" to the firmware, that were applicable to a larger user base, may have had some negative effect on the less widespread sensitivity problem I was having.
3- I like my PSR-500 a lot, but it still today will not receive as well on weak P25 700 MHz signals as my BC996T for the system I monitor. Only DSP 1.0 was as good as my 996. Recent DSP and CPU updates may have improved sensitivity slightly.
Dave