For cutting through trash the 5" in best.
The 5" though is more for doing the small trashier sections, around rocks, between roots, around trees, under bushes and other similar sections. You can use the 5" for doing the open areas but it is impractical for the long run so use it more as an accessory.
The 8" will cut through trash better than the 10", and the 8" is a preference coil too --a coil that is chosen as a primary coil-- leaving the 5", 10" and 15" as the accessory coils.
So, if you want an accessory coil that is used to work the overly trashy sections then the 5" would be a good choice. However if you want a coil that can handle trash better than the 10" and still allow for continuous use in place of the 10" then an 8" coil would be a good choice.
<b>Generally-</b> 5"- specialty coil, occasional use. 8"- preference coil, continuous use.
Just my take on it.....
GL/HH
