The Overload isn't quite new. It used to be called the 'Tim' switch on pervious versions. It's been refined in this version, before it was a very subtle difference in the subs. Spencer explains in the instructions that part of the switch's function is because some people want their octaves to sound like one big sound (i.e. the Ampeg Sub Blaster or the DOD Meatbox) and some like to hear the sub octave as distinct from the dry (i.e. OC-2, MXR Octave deluxe).
Regarding the usability of the tone, that's very subjective and some will and some won't. I personally won't use it at its fuzziest, but I will be using the Overload switch when I want to use it with a filter.
Is it worth the price tag? Only you can answer that for yourself. There are absolutely other more accessible octavers out there that'll do the job just fine. I actually plugged in my old OC-2 today and it sounded so good I did wonder for a second why I bought the Octabvre 3.33 😂