Can’t comment on the ECR but…
I have a 29+ Knard in the front of my swift and loving it…!
I have also backed the rooster project so will be going full 29+, I think it is definitely the way to go, especially now there are sensible rims such as dually’s and new tyres are coming from Maxxis and Vee Rubber.
I like the knard, it flies along and the grip is sensational but when it gets wet muddy and claggy it is not the best.