Mark King originally played 34 scale instruments; his first 2 Alembics were 34 scale. He then had 2 built with 32 scales, and he transferred that over to the Status Kingbass; the Kingbass Artist model is a 32 scale, so yes, he's been playing 32 scales for several years now.
From the interviews I've read with Mark it appears that for a while a least he got fed up of playing big-bodied basses (he's not the biggest guy, maybe 5'8 or so?); I imagine the typical Alembic Series weight can be an issue after 2 hrs on stage. He also says he's a plug-in-and-play type of guy, and doesn't like fiddling with his electronics too much. But he has also stated that whenever he's given another bass to play (providing it's set up right I assume!) he automatically thinks wow, that's great!!!, maybe just because it's different.
I'm sure if people were throwing exotic basses at me I'd be catching as many as possible. But I know what it's like, because I go through phases with instruments; I usually cycle through my basses every other month, rediscovering them and then getting fed up with them and then rediscovering them again.