I think the only real differences are the hair grade and knot angle. The 1305 is the same spec as the 830, but noticeably less soft through the knot. Vintage Scent also say the 830 has 10% more hair. If true, I think it shows the hair is probably too soft when angled out.
I reckon it's because Semogue aim to make a nice, soft 'luxury' boar, that some of them become too soft. It's early days with the 2 Omegas, but I'm finding they've both currently got a lot more grunt.
I agree about the handles, Omegas never seemed as nice. Having a wooden one here, it's clearly not as well finished as Semogue's. In their cheaper ones, I think the variants of the 620, of which there are a couple, are decent; a scrubby grade in a 50mm knot isn't going to flop out.
As for Jugs 830, if you ditch the cup, as Minorci did, you get more knot options.