The Radeon SSD is basically an ARC 100, which is a completely fine drive. It uses MLC instead of TLC of the Samsung EVO and thus has faster sustained reads and writes. The controller is a bit better on the EVO and it has some nice software features like rapid mode, but the 850 EVOs were substantially more expensive at the time then the Radeon drives.
I'm not sure why you're comparing a 1TB SSD with a 240GB SSD, the larger drives are usually faster. These are the Userbench scores of the 250GB version, where you can also see the ~50% higher throughput of the Radeon SSD:
Without RAID, it's impossible to reach 1TB/s on SATA III, as the theoretical limit of SATA III is 6Gb/s.
I was comparing my drive to yours, mine is a 1TB. And no, Samsung drives were -always- cheaper than the Radeon drives, as was shown in the Anandtech article you linked, and as I believe I pointed out on here years ago on a thread I can't find when AMD launched them.