WieWaldi
I think you're overestimating how much of an advantage it is. Like if I look at your earlier picture:
What I see is a scale pattern. The way I would read that (assuming I know that the top clef is 2 octaves higher) is to notice the starting note, notice that it's a simple scale up with a repeated note and a skip of a 3rd (did you notice that? ), and then play it with the expected rhythm. I don't really put much thinking into which specific notes I'm playing because I'm just following a pattern and noticing changes from that pattern. The only note I have to read is the starting note. In real music there is a bit more movement but the idea is similar. You only have to read some strategic notes and you infer the rest using patterns relative to your starting note. This is why I don't think having the same clef in both staves is a huge advantage. It's only a tiny advantage of consistency when finding the starting note but after that you don't really have to care.