I, too, am contemplating buying the CamRanger because I find the EyeFi card so flakey to my iPad mini.
I'm curious though if some of the issues with the EyeFi card can be attributed to lots of competing wifi networks and if this might also affect the camranger use in an urban area. I live in NYC and usually shoot interiors tethered with my Nikon D800E to my macbook pro with Nikon Capture Control. That works great but it is wired and has all the benefits and disadvantages of a wire. Now that I have an iPad, I can see that I can make do with the small jpeg preview of the EyeFi card--when it works. My experience with EyeFi here is that I constantly lose the connection except when I'm shooting a short burst. It is just too annoying for me and client. Will the CamRanger offer better performance and reliability in such a wifi network dense environment? (I'm just speculating that other competing networks may affect EyeFi performance--I have no idea--but just about anywhere in the city, I can pick up at minimum of 15 networks and usually 20-30 or more on my iPad.)
Also, can anybody comment on camera and CR battery drainage with CR? With the EyeFi card in my D800E I go through 3 camera batteries in about 5 hours with live view usage. I'm willing to buy more batteries and keep my charger with me, but just want to evaluate how much I'm really going to need to spend to preview wirelessly for a whole day shoot. Thanks for your help.