Before buying my SPJ4 (2020 build, single piece maple w/ pau ferro board) from Bass Buddha, I was wondering about this, as well: I had never heard of a Dingwall neck being made of less than five laminates before. Seemingly, the idea is to give the Super basses an even more traditional envelope. I don’t know, but I‘m no oscilloscope guy - I simply enjoy the tone and feel of the bass.
My SPJ’s neck certainly is just as stable as those of my other Dingwalls (all of them multi-laminate wenge necks). Don’t forget to take into account how Dingwall necks are built:
"However, our installation method – taught to us by Glenn McDougall of Fury Guitars, involves gluing the truss rod into the neck under almost 1000-LB of pressure."
I think this method - and Dingwall being picky regarding pieces of wood - is central to their necks' stability.