In one word. Yes. I went from 3 980's to two 1080ti's and I wouldn't have done it any other way. How could I have gone from from an older gen to brand new and have lower fps in games that need it? I run 4k as well. No way I would have stayed at 4k if I was going to run just one card. Fps isn't high enough for me. SLI is what it is. Most of the stuff I play has SLI support. I enjoy it.
Everyone says alot of things but take it from those actually running two cards at your res. 4k is to much for one card.
Nice honest answer! First ive heard with someone stating needing 1080ti sli.. usually people say rhey ran from 1080 sli to a single 1080ti and i could never understand why when 1080ti is only 20-30% faster then the non ti card.. so im trying to hold on to my 1080 sli as long as i can for 4k.