A case/bumper has never made sense to me on a phone like this. Part of the appeal is having something thin and light, and a case/bumper destroys that. That said, that bumper is nice. I wouldn't get the screen protector though, it seems unnecessary when combined with the bumper.
I never ever used a case on my 4S or my 5S.
It's just that with a much bigger phone there is a larger chance of damage and I am very paranoid of that despite being caseless for so long and with no damage.
I just thought this might be an exception since the bumper is extremely thin and fits well with the new Rose Gold 6S+.
I'm just curious of the build quality of the 6S compared to the 6.