I wouldn't buy this if you already have the other set; some of the brushes look pretty similar to me. This kit is a regular shadow brush, a crease/blending brush, and a smudge brush that, to be honest, I rarely use - I just don't smudge with a brush that much. To me, this seems like an all-you-need kit for applying powder shadows (I'm not sure how well these brushes would pick up cream color, but then I tend to apply creamy formulas with my fingers anyway). It's a great set, but if you already have brushes that do these things, why buy more?
I would say redundant. If you already have the larger set, these brushes would do the same things as those.