You know, it really depends on what you mean by 'picky' and what you mean by 'audiophile'. I find a lot of 'picky' people tend to let go the finer details of the listening experience and that many 'audiophiles' are just groupies who yearn for a new clique.
The S:Flo is a GOOD player.
On the +++ side:
Low - moderate amount of hiss
Good output when driving low or high Ω earphones
Great Line out
On the --- side:
No gapless support. (That is a big step back from OLD technology like CD and MD and newer tech like iPods.)
Low pass filter that dulls the high frequencies a bit (enough that I immediately commented on it with my DT880 and CK10).
If you have sensitive earphones, you can hear clicking noises when playing music at low volumes no matter the screen is off and has been off for a long time.
The other stuff: bubbling sound when the screen is on are just annoying. GUI is a step back because it flaunts the screen, but there is no real reason to have a touchscreen input for this player, nor such a large screen. Teclast just played to the lowest common denominator by including a huge screen and touch input. It is a clumsy way to navigate this player no matter the firmware.
shigzeo is a great contributor and valuable resource here, no question. However, to my knowledge, his impressions are of the older firmware 2.2 rather than the newer 2.3 which was basically the SQ update.
I had no issues w/ the UI. Directory, pick a folder, have a listen. No sweat. If you can manage your collection within folders its easy breezy, if you rely on software to sort your collection and don't want to mess w/ it than I would not go for the Sflo2.