I feel it’s time for an update on my current favorite unicycle since I built it a bit over a year ago.
Wheel and frame is unchanged but I’ve also come to realize that I (at least for now) enjoy flowy trails and cross country riding instead of the more technical stuff so the unicycle has been tweaked for this purpose.
The M4O Handle Saddle setup is described in more detail here but I’ve since changed the saddle to the ISM Prologue that is a bit softer than the PS 1.1 I initially used. I love this setup as it provides bike-like comfort on a unicycle for me.
Brake has been upgraded to a 4-piston setup. I initially upgraded to a Magura MT5 and used it for many months until I recently discovered that the strange noise I was hearing when pushing hard was due to the MT5 brake caliper hitting the Spirit cranks 
So now I’ve changed to Shimano BL-MT401/BR-MT420.
I used 137mm cranks for the first month. Then I used 127mm cranks for a year and last week I changed to 117mm. Kind of natural progression I guess but was quite surprised that the recent change from 127mm to 117mm gave me an instant speed boost of 10% and now my average speed on the 29" (~15km/h) is almost similar to my carbon 36" (using 137mm cranks) average speeds. With practice (by gaining confidence) I could likely increase my 36" average speeds but right now I have no motivation to do so.