Got a Korg MS-20 FS and two K-2s. They sound identical, they made me sold the FS. They also seem sturdy enough (more, at least, than a MS-20 mini).
That being said, I don’t like the brand. If Korg made an MS-20 without a keyboard (as they did on a limited run with the MS-20M), I would rather buy a Korg. But it’s out of topic.
I’ll add that the discussion about surface mounted components and repairability is doubtful. Korg also does it (A MS-20FS is almost empty). Sequential does it (open a REV2, the voices are all on the same board - 2 if you have 16 voices - and seem pretty irreparable to me). It’s not suddenly worse when Behringer does it.