Newer Shimano Nexus 8spd
From what I’ve gleaned it is an improvement over the older ones. I’ve accepted that the mod will not be cheap. I was using the “cheaper” 3-spd to off set some of the cost. I have a Downtube Mini and like the IGH flexibility.
If I got the 6-spd, I’d probably use the Kinetics kit to upgrade it to s 9spd, albeit without the IGH flexibility.