My 2-cents, hold off on OLED for (sigh) 1 more year. <----Note, just saying this is flame-bait, so everyone be "prepared" for the inevitable. :-/
But a few thoughts, most of which you've already had:
1. Absolutely get 4K.
2. Absolutely go OLED if you can (again, wait a little, but if you really can't and can afford it, go for it)
3. Be dubious of the curve. (LOL....author runs for cover).
4. Be doubtful of QD
"By Grabthar's hammer, by the suns of Warvan, you shall be avenged!"