What makes twinking a caster "great"

[Goregasmic]

For ench getting to 190ish from base cha will make a huge difference on charm stability.

Charming is a huge mana hog too so more mana always help being more efficient with charms. Started my ench from scratch and I don't know how many fights I had to tap out because charm broke 3 times or I got an add I couldn't manage. And since you're stacking cha, if you're untwinked you won't have significant int/mana before you reach 60 so getting both with twinking is a major help.