hong said:
1) What on earth is a "logical gap"?
2) What on earth does Practiced Spellcaster have to do with this thing called a "logical gap"?
OK, bad phrasing

What I mean is, it seems logical to me that multi-class spellcaster are far less powerful spellcasters than single classed spellcasters (that's my gap).
Prestige classes from 3.5, then feats like Practiced Spellcaster (or worse Precocious Apprentice) fall in and provide repeated and combinatory options which reduce that difference in power; i.e., the more books printed, the less you have to pay for versatility against specialization.
Doesn't that damage balance between classes ? What about classes which pay a dear cost for versatility, such as bards ?
Again, it seems to me that the various Mystic Theurge + feat options provide character builts more powerful than plain arcanists or divine spellcasters, which, by core rules, are the most powerful characters of the game. Doesn't it alter game balance ?
And what is the purpose of this escalation ?
Regarding Practiced Spellcaster : in a way, it's not a bad feat. Authorizes players to try some characters that didn't stand a chance before. Is balanced for many campaigns (especially when the DM goes heavy on high-HP or SR monsters). But while legitimate, in its design, to help otherwise hopeless character builts, it also open options for reinforcing or creating characters at the high end of the scale of power. In this, it damages balance. IMHO.