I live near you and monitor Chester County. As I replied to you, in another thread, the 536 is not optimal for Chester County's Harris System. Not only is simulcast an issue but Harris Systems seem to be configured in a way that makes audio intelligibility more difficult than other P25 systems. I don't know why but bet someone here can explain the technical reasons.
I suggest you purchase an SDS unit or Unication G4 or G5. My Unication is superior to my SDS 100 & 200 for the Chester County system as it manages simulcast better and produces clearer audio. The downside is the lack of scanner function flexibility.
The SDS units do a very good job with Chester (90% as good as the G5?) and offer far more flexibility. As for UHF , using the same antenna, the SDS's are just as good as my Realistic Pro-2021, Realistic Pro-2005, Realistic Pro-2006, and number of other analog receivers I have on hand. Using a paper clip I can receive receive DE county sectors 1&3 no problem...
You will not need that discone for Chester County or DE county and, in fact, it will make Chester simulcast worse given the location of the transmitter sites relative to you. A good 800mhz rubber duck is all that is required to hear Chester and DE CTY systems. I am not sure what other systems you want to hear but the 2 closest, Montgomery & Lancaster counties, are 100% encrypted. I guess you might be able to hear Wilmington DE sites but the rest of DE is also 100% encrypted. So you can ignore the comments on interference and IF issues. At our location 90% of all transmissions are 700mhz/800mhz P25 and coming from a single system. DE county's closest UHF site is almost 5 miles away; we do not live in a high RF environment.