So just confirming, you have tried the various firmware releases since I sent mine back?
***If that is the case, it would seem that your observations match what I observed in my brief time with the SDS100 in Phoenix, even after you installed several firmware revisions. And of course as you, I, and others have noted, the SDS100 cannot even begin to receive as many simulcasts from any given position, as you, I, and others have seen the G4 receive (specifically referring to simulcasts other than the simulcasts which the radio is sitting within. I mention this because these simulcasts are all in the 700 MHz band.
I strongly agree that at least here in the valley, 700 MHz performance is lacking with this device, apparently in all of the various locations you and I have tried. There must be a lot of interference that causes problems with the SDS100, at random locations all over the valley...interference that doesn't bother the 436, other digital scanners, or the Unication devices.
At this point I find it highly doubtful that a firmware revision is going to solve such significant performance issues, at least for those of us here in Phoenix.
Regarding the heat issue, I also found the level of heat to be excessive, but tolerable. More annoying in terms of physical performance, was the long charging time and short battery life. I understand that a larger battery is coming, but that will only make for a longer charge time. This device would have benefited greatly from having a rapid charging capability like modern phones have, and I suspect that more could have been done to dissipate heat more efficiently although that in itself isn't a deal-breaker for me.