I use IPBike as it has the most comprehensive set of ride metrics imaginable and seems absolutely rock solid, never dropping connections etc. If only it could be reflected over to the RFLKT! Of course, I have the same issue with the Cateye, as that unit will only accept Cateye's own app, nothing else. IPBike, for example, uses my Samsung's built-in barometric altimeter to track elevation and, although Strava seems to disregard it, TrainingPeaks uses it, so it is useful.
I'm impressed with the RFLKT; it does everything I expected of it and seems to work, for me at least, very reliably. The Cateye, though, has quite a lot extra, especially if used in the same way (ie. reflecting Cateye's phone app). The screen is marginally better, screen designing is just as flexible and it seems to 'just work'. But I also get the following, which I don't get on RFLKT: pacing arrow, on-screen compass, phone battery life indicator, phone call and SMS notifications and, as long as the reliability is there, it seems better value (it was only £15 GBP more than the RFLKT). Plus, I can buy a proper 'out front' mount for it!
I may give my RFLKT to my brother who has an iPhone 6S and will therefore be able to get the most out of the RFLKT using Cyclemeter. It is a very good product and I'm happy to recommend it.