Awesome thread! i was about to spend ALOT more on some of these until i thought, let me serach STH, i know there is a cheaper solution for this common problem...
im about to order some of the dell 4$ ones (for use in supermicro system/sm treys), so will update with how that goes- alot of the drives will be HGST sas so will be a good test of the dell converter vs thinner sata ssds (i doubt there will be any issues).
I dont like the idea of an interposer (the little sata pcb on some of these), and i have noticed the airflow issue too when using non SM converters in a 12 or 24bay sm chassis. so the $4 dell should be a nice option.
btw, one of the coolest 2.5 to 3.5's ive come across is the supermicro nvme tooless treys (latch to hold in the 2.5' drive, and it is solid/secure). they look cool (orange tab) and work very well/cleanly. they were 18$ each + ship from SM estore direct (they are reasonable on the shipping too, i think 4x of those treys + some sata cables was like 13$ fedex ship).
