There are also rumours that the 6c will have the same internals as the 5s, but only have the addition of the NFC antennae to support Apple Pay (so, those having a 5s won't have an upgrade path).I have a 5s and haven't had any issues with connectivity. One of my other apple-fan/teacher-friend has a 6 and a watch so we've been checking everything.
However, I wouldn't suggest going to a 5 or s. From the rumors I've read, there is a chance that the next iPhone launch could include a 4inch screen for people that don't want to larger size.
Wow, going from the Plus back down to the 4" size? That's quite the jump. Any time I use my wife's iPhone 5 it feels like a little toy in my hands. However, I am looking forward to jumping to the 6S later this year. 5.5" is a bit much for me so 4.7" it is. I'd be worried about jumping down to an iPhone 5 with future proofing in mind. If you're just going to use it for another year until you get another upgrade then the iPhone 5 should be ok. Otherwise get the 5S or wait for the 6S if you can manage the time and use a family member's upgrade. The 6S will have double the RAM and means it will last a really long time compared to the 5 or 5S.Curious, how is AWatch working with the iP5 units and the IOS8.3 updates?
I'm considering going back to the smaller, lighter IP5 series, from the 6-plus.
AFAIK, just the 4s, but not 4.I doubt iOS 9 will go on the 4. But there is a first time for everything.