Reassuringly dull sounds good indeed.
It seems like they don't support Lightning though so unless they can send the sats over to a different onchain address directly it's kind of a deal breaker for me.
In a high fee environment you'd be required to leave your sats there untill it makes economical sense to pay the onchain fees and depending on your stacking pace it could mean months.
Also, the fact their wallet generates and (potentially logs) the keys in the first place essentially defeats the point of being non custodual from a trust perspective.
Many points I'd need to check and so little time. Feel welcome to share what you know. Maybe I can use a refferal link later if nothing sends off my own inner alarm.