Arra question

[Circlehook]

I will be buying 2 Lami Arra's for my 2 penn 704's. My question has to do with guide width, why do some of the arra's have large diameter guides, and some have smaller? What is the advantage of a wider vs smaller, or vice versa? My quess is longer cast on the wider, but why so many with smaller ones?

confused and this is a big purchase for me.