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I'd prefer to download and have immediate access to ALL currently licensed callsigns in the region/area chosen, then simply L/O those that don't interest me or appear inactive. Lots easier and far less frustrating for this noob to simply L/O an object (for whatever reason)... than ignorantly doing without... and not realizing it. But I assume, (yet again), that I'm likely in the minority.
I'm not sure you fully comprehend what this would entail. At one point I briefly attempted to do what you are describing. However, I quickly realized that if I compiled a (non-duplicate/sorted) list of all scannable frequencies from all active FCC licenses in my area (Denver-Metro area), I would likely have TENS of THOUSANDS of frequencies to scan (if not more).
If you are really interested in identifying all active scannable frequencies in your area (not in RR), your time is better spent running your scanner in "search" mode in a particular range, and then incrementally "locking out" individual frequencies as you identify them. If you do this for any length of time, you will likely find a surprising number of active frequencies that will be difficult or impossible to associate with any specific FCC license in your area. Conversely, you will also find many THOUSANDS of frequencies in ULS which are not in active use in your area. Some of them were NEVER in use, some of them stopped being used years ago, some were moved to a friend's site tower 45 miles away without updating ULS, and some of them will be used many years in the future.
Also, sometimes you will find licensed-related documents in the "Admin" section of a ULS license entry with very, uhm, "creative" explanations of what their system is supposedly being used for (I recall reading a submission which indicated certain frequencies would be used for "public safety" purposes, when in fact it was being used by concrete trucks & construction companies...)