[Shivetya]

You can always hold your phone up to the screen and determine if a new one is going to be a bit too large...

http://www.piliapp.com/actual-size/

its not perfect, you cannot simulate wrapping your hands around the device but you can actually hold an existing device up and get a good idea of what it will be like

[nicholassmith]

Sure, and on screen the S5 might not look too big, but in my hands it felt ungainly and awkward for anything longer than a few minutes. The point I was making was that the 6+ might be a better tradeoff with less battery life but a slimmer profile to 'fit' better in hand.