ZFS: Disabling ARC?

[Quartz]

Can someone help clear up a few ZFS basics for me?

A few recent threads about ARC issues and memory-induced panics have 
made me realize I'm not 100% sure I understand ARC as well as I thought 
I did.

Say you have a ZFS file server that houses very large single files which 
are very infrequently accessed. For the sake of argument, let's say 
you're using ZFS on a home server for your family, and it holds 
exclusively a whole bunch of multi-gig bluray rips or whatever (nothing 
else). When someone wants to watch something, they copy the file to 
their desktop and watch it there. Although the family will watch several 
videos each day, any given file will only be accessed maybe once every 
couple months. (I know streaming would make more sense in real life, and 
that this example is kinda silly in general, but ignore that for now).

If I understand ARC correctly this would be a worst case scenario, 
right? Besides hogging ram, would ARC cause any problems here? Would 
disabling ARC and devoting the ram to other things be a wise idea? Is 
disabling ARC ever a wise idea?