I face lather and have a preference for smaller brushes so the 620 made sense. First shave with it was excellent, looking forward to using it again.
The 830 and 620 share the same handle. One just gets black paint/enamel on the inside while the other gets red. Well that, and the knots are different. 90% tops compared to 75% tops, if I remember correctly. The loft is different too.
The handles are ever so slightly different. 830 is round base, with eight scallops around the top of the handle, and the 620 is eight sided at the bottom, round on top: Although I did just notice my Semogue 730 (Silvertip Badger) does have the identical shape handle as the 830, but with black instead of red in the acrylic.
I know this is a late reply, but i have had two Semogue 2000 brushes have the knot just fall apart on me. It took a couple of years of daily / regular use for this to happen. That said, my favorite brush is the Semogue BC Mistura (22mm mixed badger / boar knot that came out in 2014). Never had an issue with any of their mixed or boar knots aside from the 2000.
