UPDATE
I've had a couple of days to play with my Smooth Hound system and so far I'm loving it. A couple of red bars are lit up to indicate a bit of interference since I have a WiFi booster unit about 12 feet away from the my pedalboard. Not had any dropouts though - connection has remained strong and stable (so to speak. Ha.)
One thing I did notice was that playing through my Phil Jones Bighead it seemed like I had a very faint high pitched whine when running the Smooth Hound through my fx chain and into the input. It was powered with the standard power supply, separate from the daisy chain powering my pedals. There didn't seem to be any hum when running through my practice monitor speaker though so it could just as easily have been the Bighead or something in my fx chain. I'll do a little troubleshooting later on without any of my other pedals. It was only just noticeable when I wasn't playing anything so really not a deal breaker at all.
Overall it's a lovely, streamlined system and I'm very happy with it! Oh and I took a few pictures to show the scale of the transmitter and receiver - I was surprised by how small and light they both are. They feel very well built but the receiver in particular weighs almost nothing and the heaviest thing about the transmitter is the batteries.
That's an ordinary iPhone 6, not a 6 Plus.