Took me less than one day, phone history:
iphone 3gs black [june 2011-june 2013] => samsung galaxy s4 black [5"] [june 2013-june 2015] => samsung galaxy s6 white [5.1"] [june 2015-oct 2015] => iPhone 6s+ rose gold [oct 2015-present]
With the 6s 4.7" and a case on, I realized i found I still need two hands as he case that provides protection also extends the width abit so it's as wide big as the 6s+ without the case on... which meant 1 hand using was impossible to type on the 6s so I had to 2-hand it anyway so pretty much for me both phone need to use 2 hand to get most out of it...
What made me change from 6s 4.7" to 6s+ 5.5", was because both phone need 2hand issue and also i took the better battery life phone with a better display and camera features [i really do a crap load of photography and i noticed the 6s cant render stable images well unlike the 6s+ from my testings]
so I just plunged and exchange for the 6s+ instead. Still can 1 hand scroll webpage but definitely not type with one hand one or the other... But nowadays i always use 2 hand to TEXT/msg people... because more stable, less likely to drop and be clumsy and dalso faster using 2 thumbs to type instead of one, you get so much in, its quicker...