Although this works perfectly fine with with a magician or necro, as an enchanter I find that I almost -never- have any DD spell memmed as there are far too many spells to be memorized than there are spell gems for every day enchanter stuff.
I don't think this makes sense for enchanters. When charming I lose an extremely valuable spell gem just to ping the mob for a few points of damage where it could be put to use for a stun or other useful gem that could save my life.
Velious will help with this once we can make a Blue Ceramic Band:
http://everquest.allakhazam.com/db/item.html?item=14673