Not to offend, but both frames and forks are probably made by the same Chinese company
Oh! I've no doubt that's a distinct possibility,and I'm not offended in the slightest.
Good is good whoever makes it,and whoever copies it exactly has the same product,whatever name's on it.
But if you compare the Sutra's geometry across the size range compared to the Vaya-their methods of classifying sizes are different but match up toptube lengths for a better idea-and you'll see there's only slightly differences,though the Vaya's head tube for top tube length is much longer,which is significant for comfort IMV.
The ST angle on the Vaya is 1/2 a degree slacker.
The Sutra's HT angle is 1/2 a degree slacker @71 degrees across the range.
Whereas the Salsa's geometry differs incrementally as size increases.
I've no doubt the tubes are very similar,though don't know how similar.
FWIW my Baby Blue Vaya pictured above has a slightly bigger diameter TT than the earlier (Bronze) one,and I can feel it's sliigghhttllyy stiffer as a result, which seems to indicate Salsa's development isn't static.
I don't know anything about the Kona other than what I've read and chatting to a couple of owners I've come across on my travels,but it gets good reviews.