Update:
Force stopping G-Play and then restarting it now shows the Ricoh Image Sync app for my Hudl 2.
Unfortunately the app doesn't fill the screen on the Full HD Hudl 2 screen, though it does on my Nexus 5
What happened to the little icon that you could use to expand apps to fill the screen? More investigation needed.
The good news is that Imagesync works really well on my Nexus 5, once connected you can even change the SSID and password to suit yourself, and connect by tapping the phone on the NFC symbol on the front RH of the K-S2 handgrip.
The transfers are pretty fast, it even focuses my Tamron 18-250 pretty quickly remotely.
I quite like it, and I'm loving the K-S2 even more now, it's going to make night time long exposures and shots of the ISS much easier, with the articulating screen and remote app.