Yeah, not so much. If you're 430 you haven't been playing the game much at all and you're not going to "crush" content that drops 445/455. It would be doable for skilled players who have been playing the game, but "crushing" content that drops +15/25 would be limited to a subset of mythic raiders, which is a hypothetical since they were all past 445 before 8.3 dropped anyway. A normal group of 430's will have some long boss kills early before flaming out by the midpoint.