The Experience pedal comprises of the fuzz and octave fuzz parts of the Foxx Tone Machine, but with a few slight modifications - which make for a more pronounced octave-up effect. It also features an old swell circuit from the 60s, which works with the octave fuzz section.
There is a short demo of the original Experience pedal by Doyle Bramhall II at around 5 minutes into the video below.
This allows you to use the swell in fuzz, octave fuzz, on its own - or with other pedals. (On the P450 you can only use the Swell in octave fuzz mode.)
Another option is the Dust Bunny, which is the fuzz / octave fuzz sections only, without the swell.