I love where single fins are at in design progression right now. From quite short singles to the midlength size, I've been able to synthesize old and new design principles that are shattering previous boundaries about what single fins can do. Multi-finned boards are always at their best in a turning situation, but single fins are neutral and have less drag. They don't need input to perform, allowing the surfer to "just cruise" in moments and maintain speed down the line.
Also, single fins can be turned from anywhere, where you've got to be over the fins on a multi-finned board. So single fins lend themselves to moving up and down the board to make use of the natural trim in the shape and foil. There's a purity and flow to single fin surfing that lets you do what you naturally want to do on a wave and the modern design aspects that I put in the shape lets you do that with no real limitations