IMHO the only person who can answer the "worth it" question is you.
I think if you really enjoy seeing an improvement then it really does look better. But, as the article points out- your mileage may vary.
My opinion is for most people in most situations are better off waiting for prices to come down and content to increase.
Here we are talking about a niche product in Kaleidescape and inside of the market for something like Kaleidescape I think you will find many who appreciate the improvement 4K brings.
I am waiting however. In my poking around, I've found the biggest improvement from both 4K and OLED. My primary viewing is done on a 75" LCD edge lit by LEDs. Not really the videophile choice but I have to tell you- the picture is excellent. Anyone who comes by says- wow, how come my tv doesn't look as good! (And its because they are stuck on the factory settings with the contrast and sharpness cranked, for starters). I saw a 65" OLED playing 4K from a Kaleidescape- and the improvement is noticeable. I remarked to the owner of the equipment: thanks for ruining me! But, I still think my 75" looks great and there are no OLED I am aware of yet in 75" size. The biggest place I think I would see an improvement is in my theater with a 14' wide 2.35:1 screen. However, 4K projector prices are not going to go higher, they are going to come down. And there really isn't much content. What's more, the HDR10 and Dolby Vision standards have just been adopted and its not really clear to me which one, or even if any one, will get wide adoption. I could be wrong but I've read many reports that say apparently the high dynamic range means a lower average brightness on many scenes so the image won't look quite as pleasing as one would hope.
A good friend who loves having the latest gadgets but isn't really into learning about them asked me if he should buy a new flat screen TV and my reply is: if you can hold off 12-24 months, I think you are going to be glad you did. BUT, if you just have to have it now, the 4K displays out there will definitely get you a very nice picture.
I'm waiting.