There’s such an enormous contrast between the Hydrasynths and the Osmose. You talk about how open the patch design is with the HS, which contrasts with how opaque patch design is with the Osmose. The keyboard will be more expressive on the O —the HS from Explorer to Deluxe are all ready for those added MPE dimensions - you can adapt and design patches with those added dimensions, it’s built into the HS.
The basic sounds between the two are night and day of course. Both have a range, but sit in very different sound design space. It’s a matter of personal preference, and specific need.
Then things like front panel control can be considered, quite different there. And if you’re discussing the Deluxe, it’s bi-timbal, with more voices, and more keys. It’s nice that there is a family of HSs all capable of sharing their patches.
There’s lots more quite different too, pluses and minuses both directions.