Electric Fans... Y in shroud?

[elks]

So I saw a post here while researching about using a fan out of a Cherokee. This fan was good because it fit into the factory shroud....

My question is why does it need to fit into the factory shroud? Why not just go with a set up like this from summit?

http://www.summitracing.com/parts/sum-g4908

I am thinking that with out the shroud it makes more room and clean up the bay a little. Just not sure if there is an advantage to using the factory shroud and going with the jeep fan.