I'll play this game -
I'm seriously considering the camera based on the leak for a few reasons.
My use case - I shoot almost exclusively landscapes using a 5D IV as a hobby, and I usually plan 1-3 photography focused trips per year (maybe a week long each). That can involve carrying too much glass and a tripod for maybe 3 to 6 days straight with camping gear and food. My issue is I only carry the one body with me, and at least a few times I have come a bit too close for comfort in losing my camera due to a misstep (or two). My issue is if I lose my 5D IV, there's no running to replace it for a few days and the trip is lost and over. I like the idea of having a light-weight and small secondary camera which can put out comparable image quality to the 5D IV for that "just in case" scenario. I could also see myself running both cameras at once when I'm humming and hawing over a composition or subject choice (i.e. something that needs a long lens and something that needs a wide lens).
What I like about the rumour - I love that it is half the weight of my 5D IV and much smaller. It looks as though I could add that to a bag with an EF converter for very little weight and size penalty which would amazing. For context, I've considered an M6 with a converter as well - I don't care too much about ergonomics/button layout or even the EVF if it is a secondary camera. The RP looks to be a much better fit than the M6 considering that I wouldn't need to be thinking about crop factor. I just need to be able to carry it with everything else! Also, and don't hate me for this, but I actually like how it looks! Oh, and the price. Definitely the price.
What I don't like about the rumour - LP-E17. This would be a pain for my use case - I don't want to double the batteries I'm carrying and have to leave a second charger in the car. If this used an LP-E6N I could just share batteries with the 5D IV since most of the time I'd be using one or the other and not both at once.
What I'm not sure about - is it the 6D II sensor? I had a 6D and replaced it with the 5D IV. I know DR comes up here quite a lot, but I've looked at my images from both cameras many times, and I do prefer the 5D IV outputs for editing. I'll need to see the output from the camera, because frankly the R could be a better fit if it's that big a deal to me. Though, if it's a small difference in IQ I'll need to ask myself whether it's worth the extra cash/weight/size to me.
But yes, I'm in the maybe camp. Part of me is also tempted to wait and see what the pro model looks like - maybe the 5D IV should become the backup to the upcoming camera. Well, that sounds like my GAS flaring up, so I'll leave it there!