You can program multiple sites, but the G5 will lock on to the first one it finds, and stay locked on to it until it loses signal completely. If you switch systems, it takes 5-10 seconds to lock on to a site. You also have no way to override which site the G5 chooses to monitor, nor is there any way (other than a really kludgy experimental feature in the current beta) to scan a rotation of sites. It does have a more sensitive receiver than the SDS100, but that advantage is crippled to some extent be Unication's odd decision to wire the UHF/VHF receiver (you can have one, but not both) to an internal antenna, rather than using the the SMA connector and an external antenna like they do for 800. And it's programming design doesn't allow dozens or hundreds of systems to be programmed, and selectively scanned by their proximity to your location. Except for the experimental beta scan kludge, switching systems requires manually turning an 8-position knob switch to a different setting.
If you're monitoring an 800MHz system, the G5 can do some insane stuff, I can monitor the Winchester, VA citywide 800 system from Hagerstown, MD with a BNC adapter and Remtronix 800, as long as I'm on high ground. By comparison, the SDS loses that system about 5 miles into WV going north on 81. But the G5 doesn't pick up VA-STARS with its internal antenna much better than the SDS100 does with a Diamond RH77CA. For general scanning, the SDS100 is far better, despite its less sensitive receiver. The SDS100 is good enough to reliably receive systems inside their intended coverage area, and GPS + Location Control beats pretty much everything else for mobile scanning. It also only needs 1-2 seconds to scan a trunked site, while a G5 needs more like 10.
You could think of the G5 as a sniper rifle to the SDS as a shotgun. The G5 is a special-purpose tool for hitting a specific target from long range if need be, while the SDS100 can cover a whole range of stuff, as long as you get a little closer.
