Ours is currently the pivoting MAX17, the size recommended for our displacement (and they say their recommended sizes are sufficient as a storm anchor, too).
See here for specs:
Max Marine Products - Specifications
We actually used a pivoting MAX16 for about 10 years or so on this boat, after we eventually got an electric windlass installed. I'd brought that over from a previous boat... but a dock neighbor wanted a new anchor, another member here happened to have a 17 available, the gods smiled,
E Voila!
(Prior to windlass install, we used a Fortress; first an FX-23 and then later, an FX-37, latter being slightly upsized for our boat. Both worked great. Fellow YC member wanted a 23, I wanted larger, another
E Voila!)
As to why pivoting... heh... two reasons. First is that was what was available when I was making our original purchasing decision, slightly before they introduced the other design (adjustment via scope). Second is because... seems like a useful idea, to me... whereas adjusting via scope seems less accurate, at least for me.
It also happens the pivoting adjustment can be made on deck without completely dismantling the anchor, not like the way a Fortress works. Latter is good, too, but the MAX adjustment is relatively easy with the weight of the anchor still resting on the roller and in the trough in our pulpit. Besides, I reckon I'll eventually need that adjustment SOMETIME in my life.
The "bucket" is kind of a beast, though, so may not be compatible with OPs dual-pulpit system or with a Rocna on the other roller...
-Chris