Just to chime in.
The D-21 is fully capable of shooting 2X Anamorphic
It has 2 boards so if one fails the camera can still function. I have used it with 2 recorders. One Ki Pro for Pro Res proxy, one Codex M for ARRIRAW.
Durable construction. Built to last.
Same resolutions as the Alexa just limited to 200 ISO
Makes great film like images, just don't forget the light kit.
Keep in mind the ARRIRAW from the D-21 is different from the Alexa ARRIRAW. Only found one program that can work with it. Adobe Speedegrade and Adobe discontinued it.
Hope this helps.
Best!