I dont think iam qualified to comment after joker hahaha, i mean the guy has a vast experience, i bought lots of stuff of his recommendations but since he didnt review se846 due to comfort issues, i might share some details with you..
But before this, along all my purchases i reached that performance to price ratio decreases as price go up.. meaning yes the 1000$ iem is the best i have heard but it is not 4 times better than a really good 250$ iem that outperforms its price..
Next thing thats what special about flc8s at this price range it is a great performer with the capability to tweak sound (while tweaking for me is not night and day difference but there is differences and i prefered a setting over others, also tweaking gets some time that you might get lost in the placebo effect )
Now se846 build feels better hands down, if your a bass person it will never get better than se846 bass beast it punches rumbles and shake too, but still flc8s offers tight and punchy bass of nice quality, the mids on the se846 is magical and sweet, flc8s mids doesnt have the same magic (i have no other word to describe it but magic lol) but the mids on flc8s is clear and intimate while sounding very nice, as for the treble i think flc8s would take this one as the se846 lacks in the treble department, also flc8s has this bit of air in the treble giving a sense of a bit larger soundstage ..
Thats my opinion from memory as it has been a while since i listened to se846.
And my opinion is in no way a professinal one, so i would seek other opinions as well..
But i second joker thats this would go between gr07 and se846.