When I had the RKE I used the NET module for remote access and the alarm email alerts. It supports up to 16 ports of graphing. Also you can do some programming on the outputs as long as you have the timers and alarms already setup. Timers and alarms cannot be changed via the NET. The NET is web based and does not need a app for access. I think there was a third party app on the android. There used to be be a third party one for iPhome but the guy dropped the support.
The Archon is completly web based. There is no display on the controller. It is compatible with smart phones, tablets or computers. Lindsey (pickuoman66) made some videos of programming things on the Archon. Also I am in the process of going over the Archon in my build thread here on R2R. The Archon has several input and output ports built into the unit itself, 4 switch inputs, 2 pH or ORP ports (individually selectable), 4 0-10v output ports (2 use the same connectors as the APC module), 2 PWM ports, 4 buss ports (one dedicated for the iTemp probe) and USB port for the USB drive and future expansion. It has wired and wifi network connectivity. If you don't have a network it generates it on wifi hot spot you can access with any wifi enabled device. It comes with a power pack that powers the Archon itself. It is compatible with most of the RKE/RKL modules. It is not however compatible with the NET module, RD1 or the RKE/RKL head unit. Any of these will need to be removed before hooking up the Archon to the buss.
I have 3 DP1's and use them for ATO and auto water change. So for no major issues. I have had one of them in use since I setup the tank in October 2015. I did have to have the original modified once I started using the other two which were second generation. They changed the 6v power position on the buss so it would not interfere with the iTemp on the RKL.