Would a 90 (even two hours) minute, 2 dot, double mana Sorc familiar be so bad? The 25% is an average aggregate, and I can go an entire raid mob fight without it going off once. So while in theory, it is a great boon, in practice there is no guarantee it will kick in when you need it, OR kick in too early.
Especially as Dujek said, it will further force wizards to becareful with managing their aggro lest they waste mana.
And if my guild starts giving my wiz dots for Sorc Fams, then maybe we can make the cleric comparison. Also, 3 peridots can Aego up to what? 40 people? Sorc Fams are a single person buff.
To sum up :
Sorc Familiars are a good thing, but not as great as they look on paper
Id like to see it go one of two ways :
1) Sorc Familiar has a 40-50% chance to mimic the spell of the wizard. Costs two dots, lasts 36 minutes, same or more mana cost.
2) Sorc Familar has a 25% chance to mimc the spell of wizard.
Costs twos dot, lasts 2 hours, double or 2.5x mana cost.