We probably are not hearing much from 24-70 f/4.0 owners because not many are being sold - for good reason. There are a bunch of hands-on reviews of this lens and the consensus is that it is either roughly equivalent or a very slight upgrade to the 24-105L. Here is the link to the TDP review in case you missed it.
As somebody else pointed out, it would be a decent alternative to the 24-105 if Canon had priced it around $800. But, they priced it at double that! So, you are paying an extra $800 for similar IQ, a little less distortion and CA while losing 35mm in reach. I really can't see why anybody would consider buying one once they have all the facts.
Review is one thing, actual usage is another. When I tried both the 24-105 and the 24-70mkI, I was never happy with the image quality when using them wide open, but I mostly shot at the extreme ends of the zoom. I also understand about the usefulness of having a wide range of focal lengths in a zoom, if the 28-300L wasn't so damn heavy (and white) I would have gotten it.
On your 2nd point, the 24-105 was US$1049 when I bought it. It was not $800. I apologize now but I will be frank here, and this is not directed at you, it's for anyone here. If price is the only issue for not getting the lens, then perhaps the lens is not the problem, it's your economy. Grow your economy to match how you want to spend instead of complaining about something being expensive.