Sets or Groups - Which is better?

Hello all,

Ok so in my organization we use an incredibly large hierarchy.  If I showed you the whole thing it would be about 13 columns wide and about 8,000 rows long.  So that said,  in my attached workbook I have a made up hierarchy.  It includes groups of animals:

Cats, Dogs, Elephants, Gorillas, Zebras.

Situation 1 - Let's say I wanted to create a dashboard to report the financials for contracts in the Elephant Group only?  Would it be better to use a group or a set here?

Situation 2 - Let's say that I am creating a dashboard just like the one in situation 1 but this is for the Cat Group.  The difference is that Cat's refer to their expenses as cuffed transactions. Would it be better to use a group or a set here?

Situation 3 - Let's say that I am creating a dashboard just like situation one but this is for the Zebra and Gorilla groups and the different groups will be selected one at a time based upon a parameter. Would it be better to use a group or a set here?

I have heard that sets allow you to set a condition and change dynamically and groups are more static.

Thanks,

Scott

PS - Thanks to @Michael_Hesser for the idea of using animals!