Well out of the two of us I'd guess you'll be the one that is happy about the thickness. For me the 6 got too thin to comfortably hold without a case, the slightly thicker 6S seems better from trying it out in the store, but I think it still needs to be a bit thicker so I can go back to using my phone caseless.
It has been harder to use, but I've managed caseless. I actually want it thicker just for a bigger battery.