If you disabled VHS, you will gain a bit of disk space but by doing so you open yourself up to a possibility of a most serious nature.  If you have VHS disabled and the cluster fills 100% full, through legitimate ingest or error. Jobs may stop, a failed disk will not have room to smartfail out. You may not be able to even add a new empty node to alleviate this condition. In short it is a very bad idea, and not worth the small gain IMO.
Hello,   What are the ramifications of disabling Virtual Hot Spare (VHS) on the Isilon cluster?
What are the ramifications of disabling Virtual Hot Spare?