I think comparison with Spell Penetration is a good point.
Practised Spellcaster gives in the best case twice the benefit of Spell Penetration plus longer range, longer duration, higher damage and the possibility to affect tougher foes.
Looks to me that Practised Spellcaster is a must have feat for a multiclassed caster and those feats are always a bit risky.
Tell me, wouldn't you want Practised Spellcaster when you are playing a something(4)/caster(x). I would definitely want it.
Vraister