Look carefully at both frames and you will see a big difference in weld quality.
A mate of mine has a Lynskey-built Ti456 and the quality of welding is of extremely high standard.
Yesterday, while having a mid-ride tea break at a local hotspot I was looking over two Van Nicholas frames and tbh the welds were shocking. Instead of that "stack of nickels tipped over" effect you see on high end Tig welded tube junctions the welds had been very obviously rubbed down, finished off etc. The only reason you would do this as a frame builder is to tidy up crappy welds…
Whatever claims people make about how good Van Nicholas, Chinese manufacturing is, etc.. you just can't compare a new Ti456 to the old one.
The guy welding the frame in the factory in China probably earns as much as the guy across the street in a different factory that makes rubber shoes. Why exactly should he care about quality?
By the way, I am a qualified and certified welder, so do a know a thing or two about this.
From the pic above of the broken chain/seat stay, that is poor weld penetration, no question. It's not a design fault. Every manufacturing process will have a margin of error – a "parts per million" failure rate. That welder obviously had an off day, but there's no reason to suggest it's a common fault – and compared to what I saw on the Van Nic's I know which one I'd choose!