The PSR-500/600 and RS PRO-106/197 are great digital scanners. My personal opinion is that their abiility to decode digital audio exceeds that of other scanners at this time. Of course, others will say differently.
A few things to consider if you decide to purchase one of the above-listed scanners:
1. They are significantly more sensitive on VHF and 800 Mhz than any other scanner I have ever used (including a BC396, BC996, PRO-90, 92, 95, 97). I do not know how they compare to a PRO-96/2096.
2. Along with the increased sensitivity comes the higher likelihood of front end overload by strong local transmitters (paging, TV, cell). I find this mostly happens on VHF. It is less likely that you would experience this at UHF / 800.
If you live in an urban area or an area close to a lot of high power transmitters, you may find yourself in need of a filter to attenuate an offending signal that swamps the receiver front end.
I currently have 7 trunked systems, some consisting of 5-10 sites, programmed into the scanner. So far, the 20 scanlist limit has never been a problem for me. But I can see where it would be for some. There is plenty of memory capacity to store a lot of data in these scanners, especially with the VFolders.
With that said, I would agree with David that you also should consider the fact that Uniden is coming out with an updated model of their 396 (the BCD396XT) with some signfiicant improvements, especially with regard to storage for data. The Unidens are fine scanners. I have owned both the 396 and 996.
The handheld versions of the GRE/RS scanners feel like feathers - they are nearly all plastic. I don't like them one bit, although I do have a PSR-500 handheld and some other handhelds and just live with it. The 396 is a solid handheld, and is also smaller. When you hold a 396 it actually "feels" like a substantial piece of equipment. I don't know if the 396XT will do the same or not.
David is a huge proponent of location-based scanning, where I on the other hand could care less. He has convinced me though that this can be a very useful feature for those who travel a lot. So that is something to consider as well - If you will travel mobile a lot and would like a scanner that can turn off certain systems and turn other ones on as you leave one coverage area and enter another, you're only option is a Uniden.
I would never ever give up my PRO-197 base/mobile digital scanner. I love nearly everything about it (aside from its ability to attract unwanted signals - i.e. overload). It does everything I need it to do, and the sound quality of the digital audio is great.
NOTE: You should look around and read about the various trunked systems you are wanting to monitor. If any of those systems are digital systems that are also simulcast systems, then you could experience problems with simulcast distortion - and those problems would exist regardless of the brand of scanner you have.
Mike