I spoke with admins about this idea over a year ago, they strictly said NO because of "Reasons".
But I do think it would be fair. I have 5 characters and all of them took different amounts of Katas to get 6/6. Some took around 100, other just 12 runs for a full 6/6.
I know people who went almost 200 times and still didn't get full set.
Personally, I wouldn't find it "unfair" to those who did 100+ runs to get a full set. Exchanging 100 Hyperion pieces for a piece is a fair idea.