6 plus user here.
at first i thot it was big too. it still is big for my hands but it's a joy to read all forms of text on it. less squinting n straining of the eyes.
can enjoy videos better on a bigger screen. again, not squinting or straining.
battery, can last a day depending on ur usage behaviour. i've ever done going for 2 days on a single charge. big diff compared to ip5 where i need to charge at least twice daily.
anyway since u already lean towards ip6, go for it. if u dont like it, can always sell n upgrade.