The ABS M1 is basically a Filco with XM, ALPS-compatible switches and 2 KRO. It's a good keyboard, to be sure, but the switches were pretty mediocre. The Das has much better switches in the Cherry blues (and browns in the "silent" version), and Metadot has fixed the firmware in the "S" model, thus putting right on par with the Filco as far as all the testing done around here shows. If I had to spend money on one or the other right now, I would pick the Das every day of the week. Keep in mind, too, that the same OEM makes the Das, Filco and ABS. Somehow, though, they were able to bork the firmware on the Das and ABS at one time.