A tablet running Skydemon is not a replacement to my GNS430 but an addition, I cannot take the GNS430 home and do flight planning on it. The map on the GNS is prehistoric compared to SD. The GNS is fine flying airways or doing approaches. SD shines during the airways-to-VFR field transitions such as EDFE where you need to do several miles of precision VFR navigation after being dumped out of controlled airspace.
I have terrain warning on both GNS and SD. If the GNS would fail completely I would be happy to fly home or anywhere else on SD alone. My Android tablet has never overheated in about 2.5 years of use. I lost GPS signal a couple of times until I switched to a Bluetooth WAAS GPS receiver at a cost of about 80€.
In my opinion SD is not a replacement for a paper chart either, but I don't do WW2 navigation any more except to show young people how it was done.
I prefer to follow the magenta line, on the GNS supplemented by SD, while looking out for traffic while VFR and taking care not to infringe any airspace I am not cleared to enter. Only a few percent of my time airborne is spent watching the moving map on the tablet. I find it liberates me, keeps the NOTAMs available and most frequencies are only a tap away. There is rarely any concern about whose airspace I am in right now or in 5 minutes.
The fact that it is not a certificate piece of equipment means that progress and new features are added quickly and customer wishes are taken into account, sometimes days after making suggestions.