Summarizing and clarifying a few comments earlier in this thread:
V-Control Pro is still free and runs on an iPad. It is stable and controls the transport and arming tracks very well.
V-Control Pro 2 is, as mentioned, a yearly subscription and requires iLok. One reason for getting it is that it includes V-Console that runs on an iPhone, again for transport and arming control. The website lists DAWs that are supported and SONAR is not currently one of them (it is planned). However, I spent some time communicating with their Support and was able to get V-Console to work fine with SONAR on the iPhone. The problem is the settings would not save, so I'm still waiting for the supported version that can be loaded once.
Each of these apps is a specially-designed screen to provide control of SONAR (or some other DAW) and as such are easy to see and use. The few times I've experimented with remote control of the PC, the screen is so hard to read and so difficult to select individual items that I find it useless.
I also am a former user of the Frontier Design Tranzport, a nifty device in its day that was abandoned, software-wise. The app approach on an iPad is so superior to the Tranzport that I abandoned the Tranzport long before the company abandoned me.