Yes, I have felt it is a bit of a side grade. I am only gaming on it so i'm not sure if i'm too worried about going dual channel from quad channel is too big of a deal. But yes, mainly it is something new to play around with. Plus I love the look of the Code board. Just don't want to let my desire to have something new to play with mean I actually end up with "less" of a system.
I have an 8700K and Hero board already on another one of my PC's and love it. Makes my X99 system feel like a dinosaur.
Been a long time loyal SLI purchaser but, like you, I am tired of the 2nd gpu sitting there doing nothing. The few games that do support it, suck, the good one's don't support it lol. A 1080Ti I have on my separate 8700K system handles 4K gaming quite well. I don't feel like I am missing out on anything not having a 2nd 1080Ti on it.
That is why I think the 8700K system makes sense in away over my X99 because even though I would put both Titan X's on it, the 2nd one would sit there doing nothing anyways. The occasional game I do find that runs SLI, well its still better then 1 even at 8x/8x.