That's good to hear, a 4inch with the specs of a 6S would be a godsend. I would probably pay for that separately if I am unable to get rid of the 6S for whatever reason.
I should of mentioned, it is a monthly contract on EE via a broker (mobiles.co.uk). I'm paying £24.99/month + £125 upfront for the 64GB 6S. (Was £50 upfront for 16GB but I thought rather be safe than sorry. The irony of my life is that I have only used 3.8GB data and I won't use anymore than this ever lol). At the price I'm paying I think it might be worth holding out. The phone is currently still in it's plastic manufacturers seal, though the sim card has been in use for 2 days. I recall the terms suggesting that a phone can't be returned after insertion of a sim card.
Based on this I'm just planning on using it for 6 months, since EE I believe don't allow unlocks prior to that and by then a 5SE should have released.