Bought one of the P33110 for my
X10SDV-7TP4F (the Flex ATX has the 110mm slot), but in a moment of weakness picked up a couple of open box
X10SDV-4C-TLN2F, where the mini-ITX only takes the 80mm. Debating on just converting to a miniSAS HD and picking up a U.2 drive, or experimenting with some funky NGFF extender/riser to allow the 110mm.
Thanks for the link to the S3500 m.2. That is perfect for the (also open box impulse purchase)
ASRock D1541D4U-2T8R I have incoming.