Thinner rad usually mean more FPI (Fins per inch) and needs faster/louder fans, so yes it would, but it might be noisier.
A good alternative is the Swiftech rads, which offer performance inbetween thick low fpi rads which are better with low speed fans, and thin high fpi rads that are better with high speed fans.
Either way you can improve the performance of a dual thinner rad with either 2 lots of fans in a push/pull config or putting a shroud between the fans and the radiator. Both give around 15-30% improvements depending on setup.