I will, for sure. I was having pretty good sales on the other vendors, but a few authors I knew went all in on KU and they had pretty good results. I thought I'd give it a try. Was tough getting the courage to pull out of the other vendors - especially Kobo and Apple, but it'll be a good experiment.
I'm a newbie here but I'll share my KU results if you're interested.
I write contemporary western romance, mid-level heat. I was wide with one book for about a month and a half, and when my sales had trickled to next to nothing (on all platforms, including Amazon!), and I knew I had nothing coming out for another couple of months, I opted into KU.
I had a new release in January, which I put wide for the handful of readers I knew I had who read on other platforms, for about a week, then opted in. I also ran three free days on book 1 with a few ($15 worth) email list ads around the same time the new release came out. I gave away 11,000 books in those three days and sat at the top of the free western romance list and as high as 24 on the free kindle store list.
In 2015, not including April yet (I wait for official figures from Amazon), I have sold 508 books (300+ of these were in January with the new release and the elevated sales ranking)... I have had 1006 KU borrows that paid. My KU income works out, on an average month, to be about 2/3rds of my income.
I'm not an expert by any means but because I am a newly released author, I feel KU is working to my advantage, putting me in front of readers that may become sticky enough that I carry them through the rest of the series with me. I have another book coming out (probably, depending on how quickly my CP, betas and editor work!) by the end of this month, and plan to go wide with everything on my fourth book, crowning it all off with a BookBub ad.
For someone new without a backlist, I think KU is invaluable. If you're already doing well with sales and a backlist of 4-6 books in a sticky series on all platforms, I can't see it being that beneficial. But for me, it's quietly collected 200 newsletter subscribers since September and paid for my wedding dress, so I can't complain.