So you need 150 different operation systems on your usb and computer ? I'm just fine with creating usb stick with most recent version of os when i need. And i think most people feels the same way...

If i can solve my problem with software and ordinary (=cheap) hardware, why should i pay 10 times more ?

YUMI does this apperently. I had never heard of Yumi before, but I read the comments (and the article) so now I know about it.

So given our new knowledge what does this do that yumi does not?

Yumi uses GRUB directly for the boot, so I believe it's limited to Linux only (AFAIK, Grub can't direct boot an iso)

Unless things have changed GRUB can boot other operating systems.

Grub can boot just about anything... Windows included.