I have used print-your-own decal papers, and the biggest problem I had was the thickness of the final decal. With sufficient varnish to ensure the ink doesn't bleed in the water they ended up a very visible film. Using on 1/22 scale I got away with it, but on 1/76 the decal was obliterating surface detail I wanted to keep.
I could have been using the Wrong Paper, but after this, my experience is that'll I'll happily buy transfers if I need something that doesn't come with the kit.