We use a double V belt setup on Aftershock- never had any issues with it. We went for that setup for the reasons listed above- they give just enough slip under impact but still allow us to get up to speed in under 2 seconds.

We've got a 40mm dia EN8 shaft. Really nice stuff and still like new after all of those big hits

Aftershock doesn't use bearings- we opted to make our own Phosphur Bronze bushes- we've got a set inside the disc and the pulley and a second set inside the bulkheads. We went down this route so that we had redundancy built in in case one set of bushes failed. In the end they all survived pretty well and we'll be keeping this setup going forward.

I'll try and get some decent photos of our setup uploaded to the website.