I switched to the plus twice. Longest I lasted was 2 days. I have huge hands and even still I couldn't stand that I was not able to reach the upper left corner one handed with my thumb. So many things were a stretch one handed and I refuse to have to shift the phone in my hand just to make it work. I realize there are times you can swipe to get to the next screen, or use the double tap feature, but I found I was continually having to think about my next move without just mindlessly doing it.
There are many, many who have switched from the 6 to the 6 plus and love it. It is a fantastic device and I imagine you will love it. I personally couldn't do it. Just wasn't comfortable for me unless I was sitting down using it with two hands.