I ended up grabbing an SL73, dimensions are pretty much the same as the Vivo S1 (a tad deeper) with a handful of keys more still, and it's a TP/100LR bed which should be fine. A little bit heavier (11.5 vs 8.5 Kg.), but it will always go by car so not a problem. And obviously no sounds, which was not important here anyway.
This will be the mother for my iPad Air M1, and when needed also for my MPC Key 37, while travelling, and in addition a possible second tier in other situations in the future.
Moreover it saved me quite a bit of cash... The Vivo S1 is still a hot little number, but I can have a lot of fun for 1000€ ..
Should I for some reason not feel comfortable with it (there seems to be split opinions about the action in general), I grabbed it on Amazon and can return it without any questions asked.