The 800 is local the Vhf is approximately 18 -20 miles. On the 800 system the tower is 3 miles from me and I have many times been to the different sites. The Unidens have always experienced decoding issues. Before rebanding when the PD patched two dispatch talk groups together it would cause the Unidens to pickup ambulance to ER traffic on the PD dispatch tg's.
Actually contrary to popular belief that more interference is proof of increased sensitivity and based on personal field test the Unidens are more sensitive on VHF Hi but due to better filtering they fare better . At 800 mhz both brands are of comparable sensitivty but once again due to better filtering the Unidens suffer less interference. If you would like to read more on this topic it is covered in marksscanners.com.
Nice to read a voice of reason here.
I too have access to calibrated service monitors and I too have done sensitivity comparisons between the PSR600 & PSR500 and the BCD996XT & BCD396XT. In each case and on all bands, the Uniden scanners were more sensitive.. The Uniden scanners also have better front end bandpass filtering and dual 1st IF SAW filters which adds up to less IMD in the presence of very strong in band signals.
In my experience, the GRE scanners have a fairly crude RF architecture which leads to poor performance on anything other than a telescopic whip or a rubber duck antenna.
That said, there is some merit in the argument that the GRE P25 decoder produces better audio than the Uniden, the GRE/Whistler CTCSS and mute circuits work faster/better and the audio stage has a less 'bassy' characteristic due to better high frequency response.
I hope one day, Whistler gets the opportunity to invest more time into redesigning the RF stages on their scanners, because with increasingly congested bands and increasing signal levels, it doesn't matter what bells and whistles you add into the software and UI, if the RF stages are being overloaded, nothing is going to work.