My experience with the PSR800 is that I don't get an hour out of the batteries, on average, scanning a bunch of conventional channels, one Motorola trunk system, and one P25 trunk system. These are the supposed "uber" batteries, Sanyo Eneloops, charged in a Maha/Powerex charger. My 396XT scanning the same stuff gets well over 24 hours on the same batteries - technically less batteries, as the Uniden uses 3 cells while the GRE uses 4.
The GRE has some features that are nice, like radio and TG IDs on conventional P25 channels without having to program silly "one-frequency trunk" systems like the 396 needs. The GRE would appear to handle multi-site trunking better too (sampling control channels and tuning the strongest, which is similar to how trunking radios do it; the Uniden radio tries to tune any CC unlocked/in range regardless of its relative signal strength). Some people find the GRE's method of using "scan lists" more favorable than the Uniden "system/group/channel" theory. In the GRE, you could have a scan list called "Fire Dispatch" and have conventional frequencies and talkgroups from several different trunk systems in that scan list, and listen to them all at the same time. In the Uniden, your top-level definition is a system, i.e. a large group of conventional channels, or a single trunk system, etc. Two different philosophies on how to categorize what you want to hear. The PSR-800 has the ability to record channels to a microSD card, and has the full RadioReference database onboard (so long as you continue to update it with the included software).
Scanners are not really going to have any improved range or "power" between their base and handheld versions other than the fact that the base one is generally in a stable location and may have a better antenna on it. Speaking of antennas, my current favorite is the
Diamond RH-789/SRH-789 (URL links to the product page on Universal Radio). The SRH version has an SMA connector, good for the modern Uniden radios (396/996, HP, etc); the RH version has a traditional BNC connector, which will fit the PSR-800. The antenna can telescope out and "tune" to the desired frequency band, and has a 90° hinge just above the connector, so you could use it on a HomePatrol or base station scanner with the antenna pointing straight up and down. They have excellent range (I can pick up a P25 control channel from >30 miles away with my 396XT with it).
For you, with the Ontario Fleetnet system and a large amount of conventional and some P25, it all boils down to which scanner do you like better. There's nothing really in your region that precludes you from using one radio over the other. The only thing that might contradict that statement is the introduction of more P25 Phase II (TDMA) systems. IIRC, the Metrolinx (ex GO Transit) system runs some TDMA channels. The PSR-800 is the only radio on the market right now that will handle TDMA. Rumors and speculation imply that the next scanner that Uniden announces will have to support TDMA to remain relevant, but no hard confirmation has been given yet.
Last but not least, with GRE's implosion and ultimate buyout by another company, no one is making PSR-800s any more, and people have panic-bought just about every one left. If you find anyone willing to part with one, you will have to divorce yourself from a large sum of money for it, most likely.
