A couple relevant threads for context are:
Why are disc brakes good for a unicycle?
This project should give the unicycling community important new information which we can use to make future decisions. There’s always the chance that something like this simply remains a novelty but even if that’s the case we can still learn from it. I haven’t ridden a 36" freewheel unicycle but I have ridden 20" and 26" freewheel unicycles and a 36" fixed wheel unicycle. I believe the 36" freewheel will be more stable at higher speeds, will roll over obstacles more easily, and there’s a good chance it will be easier to coast than smaller wheels. However, it will also be more prone to UPDs. I think there will also be an opportunity to pedal more on the 36" than smaller wheels. On a 26" even slight pedaling on flat ground quickly gets up to speeds where you no longer need to pedal. I wonder if the 36" will be more like pedaling a small wheel up a slight incline which is relatively easy.
One reason I haven’t built a 36" freewheel yet is I don’t have a great place to practice it. I wouldn’t want to start out on the street. A low usage road or bike path would be great but that’s not available to me. I’m also planning on building a 3.8x fixed gear 20" freewheel unicycle around December. That may have some of the projected benefits of a big wheel (in this case a virtual 76" wheel).
I’m not sure how useful it would be for a 36" freewheel unicycle but I threw together a quick tutorial video from footage I shot on 6/23/2013. I already was able to ride fairly well but the first half of the video I’m doing switch stance for extra authenticity.