Well, I'll be the contrary person here. I love set triggers, specifically double-set triggers. Once you get used to them, they allow a magnificent let-off.
As an aside, stores around here stopped selling wide shoes, which I need. The salesmen almost always say, "Oh, our shoes run wide." They NEVER fit me, as I actually need wide. If you are used to double-set triggers, a single trigger will never be the same as a set trigger. "Our single trigger runs light" is almost never appealing to me.
Single-set triggers are fine, and Winchester used them a lot. The issue I hear in longrifles is that single-set triggers are often tall from trigger plate to top of blades, making a slim rifle hard. If I misheard that, please correct me.
Nothing wrong with single triggers, but I happen to like double-sets. I really don't think someone should be slighted because they happen to prefer set triggers. On a pre-constructed gun like a Kibler, I can see the issue with adding set triggers. It seems like it would be a lot of work, and perhaps require a new trigger guard (plus inletting issues).
Just my 2 cents worth. Best wishes, Marc