Just imagine a travel bag with the two cans of soda and a nice fat sandwich. Only the sandwich is an RF mount camera, and the cans of soda are a 24-105 F4L IS AND 70-200 F4L IS. Maybe you're a little worried you'll need a night time snack, so you throw a pack of cookies in the bag. Only the cookies are actually an RF 35 F1.8.
One lusty, compact, lightweight situation you'd have going on there. For me, that's the draw of this lens. Smaller, lighter, better. I'm looking forward to the reviews. I have the 70-200 F4 L IS V1 and it is great. So if this is better, I may not be able to resist for too long. I'm looking forward to seeing some reviews hit.
Although not using a snack reference... I mentioned a similar loadout. For me the entire draw to it is size/weight/quality, and the cons are price and aperture (the aperture is reasonable for size, but I think they could have done a bit better on the price). However I don't know that I would want it over the 2.8 if I could only chose one. Then again, I might be self justifying holding off on it .